ctraits.c

/******************************************************************************
*
*  Description: C based implementation of the Traits package
*
*  Copyright (c) 2005, Enthought, Inc.
*  All rights reserved.
*
*  This software is provided without warranty under the terms of the BSD
*  license included in enthought/LICENSE.txt and may be redistributed only
*  under the conditions described in the aforementioned license.  The license
*  is also available online at http://www.enthought.com/licenses/BSD.txt
*
*  Thanks for using Enthought open source!
*
*  Author: David C. Morrill
*  Date:   06/15/2004
*
******************************************************************************/

/*-----------------------------------------------------------------------------
|  Includes:
+----------------------------------------------------------------------------*/

#include "Python.h"
#include "structmember.h"

#include "py2to3.h"

/*-----------------------------------------------------------------------------
|  Constants:
+----------------------------------------------------------------------------*/

static PyObject * class_traits;        /* == "__class_traits__" */
static PyObject * listener_traits;     /* == "__listener_traits__" */
static PyObject * editor_property;     /* == "editor" */
static PyObject * class_prefix;        /* == "__prefix__" */
static PyObject * trait_added;         /* == "trait_added" */
static PyObject * empty_tuple;         /* == () */
static PyObject * empty_dict;          /* == {} */
static PyObject * Undefined;           /* Global 'Undefined' value */
static PyObject * Uninitialized;       /* Global 'Uninitialized' value */
static PyObject * TraitError;          /* TraitError exception */
static PyObject * DelegationError;     /* DelegationError exception */
static PyObject * TraitListObject;     /* TraitListObject class */
static PyObject * TraitSetObject;      /* TraitSetObject class */
static PyObject * TraitDictObject;     /* TraitDictObject class */
static PyObject * TraitValue;          /* TraitValue class */
static PyObject * adapt;               /* PyProtocols 'adapt' function */
static PyObject * validate_implements; /* 'validate implementation' function */
static PyObject * is_callable;         /* Marker for 'callable' value */
static PyObject * _HasTraits_monitors; /* Object creation monitors. */
static PyObject * _trait_notification_handler; /* User supplied trait */
                /* notification handler (intended for use by debugging tools) */
static PyTypeObject * ctrait_type;     /* Python-level CTrait type reference */

/*-----------------------------------------------------------------------------
|  Macro definitions:
+----------------------------------------------------------------------------*/

/* The following macro is automatically defined in Python 2.4 and later: */
#ifndef Py_VISIT
#define Py_VISIT(op) \
do { \
    if (op) { \
        int vret = visit((PyObject *)(op), arg);        \
        if (vret) return vret; \
    } \
} while (0)
#endif

/* The following macro is automatically defined in Python 2.4 and later: */
#ifndef Py_CLEAR
#define Py_CLEAR(op) \
do { \
    if (op) { \
        PyObject *tmp = (PyObject *)(op); \
        (op) = NULL;     \
        Py_DECREF(tmp); \
    } \
} while (0)
#endif

#define DEFERRED_ADDRESS(ADDR) NULL
#define PyTrait_CheckExact(op) ((op)->ob_type == ctrait_type)

#define PyHasTraits_Check(op) PyObject_TypeCheck(op, &has_traits_type)
#define PyHasTraits_CheckExact(op) ((op)->ob_type == &has_traits_type)

/* Trait method related: */

#if PY_MAJOR_VERSION < 3
#define TP_DESCR_GET(t) \
    (PyType_HasFeature(t, Py_TPFLAGS_HAVE_CLASS) ? (t)->tp_descr_get : NULL)
#else
#define TP_DESCR_GET(t) \
    ((t)->tp_descr_get)
#endif

/* Notification related: */
#define has_notifiers(tnotifiers,onotifiers) \
    ((((tnotifiers) != NULL) && (PyList_GET_SIZE((tnotifiers))>0)) || \
     (((onotifiers) != NULL) && (PyList_GET_SIZE((onotifiers))>0)))

/* Python version dependent macros: */
#if ( (PY_MAJOR_VERSION == 2) && (PY_MINOR_VERSION < 3) )
#define PyMODINIT_FUNC void
#define PyDoc_VAR(name) static char name[]
#define PyDoc_STRVAR(name,str) PyDoc_VAR(name) = PyDoc_STR(str)
#ifdef WITH_DOC_STRINGS
#define PyDoc_STR(str) str
#else
#define PyDoc_STR(str) ""
#endif
#endif
#if (PY_VERSION_HEX < 0x02050000)
typedef int Py_ssize_t;
#endif

/*-----------------------------------------------------------------------------
|  Forward declarations:
+----------------------------------------------------------------------------*/

static PyTypeObject trait_type;
static PyTypeObject has_traits_type;

/*-----------------------------------------------------------------------------
|  'ctraits' module doc string:
+----------------------------------------------------------------------------*/

PyDoc_STRVAR( ctraits__doc__,
"The ctraits module defines the CHasTraits and CTrait C extension types that\n"
"define the core performance oriented portions of the Traits package." );

/*-----------------------------------------------------------------------------
|  HasTraits behavior modification flags:
+----------------------------------------------------------------------------*/

/* Object has been initialized: */
#define HASTRAITS_INITED      0x00000001

/* Do not send notifications when a trait changes value: */
#define HASTRAITS_NO_NOTIFY   0x00000002

/* Requests that no event notifications be sent when this object is assigned to
   a trait: */
#define HASTRAITS_VETO_NOTIFY 0x00000004

/*-----------------------------------------------------------------------------
|  'CHasTraits' instance definition:
|
|  Note: traits are normally stored in the type's dictionary, but are added to
|  the instance's traits dictionary 'trait_dict' when the traits are defined
|  dynamically or 'on_trait_change' is called on an instance of the trait.
|
|  All 'anytrait_changed' notification handlers are stored in the instance's
|  'notifiers' list.
+----------------------------------------------------------------------------*/

typedef struct {
    PyObject_HEAD               /* Standard Python object header */
        PyDictObject * ctrait_dict; /* Class traits dictionary */
        PyDictObject * itrait_dict; /* Instance traits dictionary */
    PyListObject * notifiers;   /* List of 'any trait changed' notification
                                   handlers */
    int            flags;       /* Behavior modification flags */
        PyObject     * obj_dict;    /* Object attribute dictionary ('__dict__') */
                                /* NOTE: 'obj_dict' field MUST be last field */
} has_traits_object;

static int call_notifiers ( PyListObject *, PyListObject *,
                            has_traits_object *, PyObject *, PyObject *,
                            PyObject * new_value );

/*-----------------------------------------------------------------------------
|  'CTrait' flag values:
+----------------------------------------------------------------------------*/

/* The trait is a Property: */
#define TRAIT_PROPERTY 0x00000001

/* Should the delegate be modified (or the original object)? */
#define TRAIT_MODIFY_DELEGATE 0x00000002

/* Should a simple object identity test be performed (or a rich compare)? */
#define TRAIT_OBJECT_IDENTITY 0x00000004

/* Make 'setattr' store the original unvalidated value */
#define TRAIT_SETATTR_ORIGINAL_VALUE 0x00000008

/* Send the 'post_setattr' method the original unvalidated value */
#define TRAIT_POST_SETATTR_ORIGINAL_VALUE 0x00000010

/* Can a 'TraitValue' be assigned to override the trait definition? */
#define TRAIT_VALUE_ALLOWED 0x00000020

/* Is this trait a special 'TraitValue' trait that uses a property? */
#define TRAIT_VALUE_PROPERTY 0x00000040

/* Does this trait have an associated 'mapped' trait? */
#define TRAIT_IS_MAPPED 0x00000080

/* Should any old/new value test be performed before generating
   notifications? */
#define TRAIT_NO_VALUE_TEST 0x00000100

/*-----------------------------------------------------------------------------
|  'CTrait' instance definition:
+----------------------------------------------------------------------------*/

typedef struct _trait_object a_trait_object;
typedef PyObject * (*trait_getattr)( a_trait_object *, has_traits_object *,
                                     PyObject * );
typedef int (*trait_setattr)( a_trait_object *, a_trait_object *,
                              has_traits_object *, PyObject *, PyObject * );
typedef int (*trait_post_setattr)( a_trait_object *, has_traits_object *,
                                   PyObject *, PyObject * );
typedef PyObject * (*trait_validate)( a_trait_object *, has_traits_object *,
                              PyObject *, PyObject * );
typedef PyObject * (*delegate_attr_name_func)( a_trait_object *,
                                             has_traits_object *, PyObject * );

typedef struct _trait_object {
    PyObject_HEAD                    /* Standard Python object header */
    int                flags;        /* Flag bits */
    trait_getattr      getattr;      /* Get trait value handler */
    trait_setattr      setattr;      /* Set trait value handler */
    trait_post_setattr post_setattr; /* Optional post 'setattr' handler */
    PyObject *         py_post_setattr; /* Python-based post 'setattr' hndlr */
    trait_validate     validate;     /* Validate trait value handler */
    PyObject *         py_validate;  /* Python-based validate value handler */
    int                default_value_type; /* Type of default value: see the
                                              'default_value_for' function */
    PyObject *         default_value;   /* Default value for trait */
    PyObject *         delegate_name;   /* Optional delegate name */
                                        /* Also used for 'property get' */
    PyObject *         delegate_prefix; /* Optional delegate prefix */
                                        /* Also used for 'property set' */
    delegate_attr_name_func delegate_attr_name; /* Optional routine to return*/
                                  /* the computed delegate attribute name */
    PyListObject *     notifiers; /* Optional list of notification handlers */
    PyObject *         handler;   /* Associated trait handler object */
                                  /* NOTE: The 'obj_dict' field MUST be last */
    PyObject *         obj_dict;  /* Standard Python object dictionary */
} trait_object;

/* Forward declarations: */
static void trait_clone ( trait_object *, trait_object * );

static PyObject * has_traits_getattro ( has_traits_object * obj,
                                        PyObject          * name );

static int has_traits_setattro ( has_traits_object * obj,
                                 PyObject          * name,
                                 PyObject          * value );

static PyObject * get_trait ( has_traits_object * obj,
                              PyObject          * name,
                              int                 instance );

static int trait_property_changed ( has_traits_object * obj,
                                    PyObject          * name,
                                    PyObject          * old_value,
                                    PyObject          * new_value );

static int setattr_event ( trait_object      * traito,
                           trait_object      * traitd,
                           has_traits_object * obj,
                           PyObject          * name,
                           PyObject          * value );

static int setattr_disallow ( trait_object      * traito,
                              trait_object      * traitd,
                              has_traits_object * obj,
                              PyObject          * name,
                              PyObject          * value );

/*-----------------------------------------------------------------------------
|  Raise a TraitError:
+----------------------------------------------------------------------------*/

static PyObject *
raise_trait_error ( trait_object * trait, has_traits_object * obj,
                                    PyObject * name, PyObject * value ) {
    PyObject * result;

    /* Clear any current exception. We are handling it by raising
     * a TraitError. */
    PyErr_Clear();

    result = PyObject_CallMethod( trait->handler,
                                  "error", "(OOO)", obj, name, value );
    Py_XDECREF( result );
    return NULL;
}

/*-----------------------------------------------------------------------------
|  Raise a fatal trait error:
+----------------------------------------------------------------------------*/

static int
fatal_trait_error ( void ) {

    PyErr_SetString( TraitError, "Non-trait found in trait dictionary" );

    return -1;
}

/*-----------------------------------------------------------------------------
|  Raise an "attribute is not a string" error:
+----------------------------------------------------------------------------*/

static int
invalid_attribute_error ( void ) {

    PyErr_SetString( PyExc_TypeError, "attribute name must be string" );

    return -1;
}

/*-----------------------------------------------------------------------------
|  Raise an "invalid trait definition" error:
+----------------------------------------------------------------------------*/

static int
bad_trait_error ( void ) {

    PyErr_SetString( TraitError, "Invalid argument to trait constructor." );

    return -1;
}

/*-----------------------------------------------------------------------------
|  Raise an "cant set items error" error:
+----------------------------------------------------------------------------*/

static PyObject *
cant_set_items_error ( void ) {

    PyErr_SetString( TraitError, "Can not set a collection's '_items' trait." );

    return NULL;
}

/*-----------------------------------------------------------------------------
|  Raise an "invalid trait definition" error:
+----------------------------------------------------------------------------*/

static int
bad_trait_value_error ( void ) {

    PyErr_SetString( TraitError,
        "Result of 'as_ctrait' method was not a 'CTraits' instance." );

    return -1;
}


/*-----------------------------------------------------------------------------
|  Raise an invalid delegate error:
+----------------------------------------------------------------------------*/

static int
bad_delegate_error ( has_traits_object * obj, PyObject * name ) {

    if ( !Py2to3_SimpleString_Check( name ) ) {
        return invalid_attribute_error();
    }
    PyErr_Format(
        DelegationError,
        "The '%.400" Py2to3_PYERR_SIMPLE_STRING_FMTCHR "'"
            " attribute of a '%.50s' object"
            " delegates to an attribute which is not a defined trait.",
        Py2to3_PYERR_PREPARE_SIMPLE_STRING( name ),
        Py_TYPE(obj)->tp_name
    );
    return -1;
}

/*-----------------------------------------------------------------------------
|  Raise an invalid delegate error:
+----------------------------------------------------------------------------*/

static int
bad_delegate_error2 ( has_traits_object * obj, PyObject * name ) {

    if ( !Py2to3_SimpleString_Check( name ) ) {
        return invalid_attribute_error();
    }

    PyErr_Format(
        DelegationError,
        "The '%.400" Py2to3_PYERR_SIMPLE_STRING_FMTCHR "'"
            " attribute of a '%.50s' object"
            " has a delegate which does not have traits.",
        Py2to3_PYERR_PREPARE_SIMPLE_STRING( name ),
        Py_TYPE(obj)->tp_name
    );
    return -1;
}

/*-----------------------------------------------------------------------------
|  Raise a delegation recursion error:
+----------------------------------------------------------------------------*/

static int
delegation_recursion_error ( has_traits_object * obj, PyObject * name ) {

    if ( !Py2to3_SimpleString_Check( name ) ) {
        return invalid_attribute_error();
    }

    PyErr_Format(
        DelegationError,
        "Delegation recursion limit exceeded while setting"
            " the '%.400" Py2to3_PYERR_SIMPLE_STRING_FMTCHR "'"
            " attribute of a '%.50s' object.",
        Py2to3_PYERR_PREPARE_SIMPLE_STRING( name ),
        Py_TYPE(obj)->tp_name
    );
    return -1;
}

static int
delegation_recursion_error2 ( has_traits_object * obj, PyObject * name ) {

    if ( !Py2to3_SimpleString_Check( name ) ) {
        return invalid_attribute_error();
    }

    PyErr_Format(
        DelegationError,
        "Delegation recursion limit exceeded while getting"
            " the definition of"
            " the '%.400" Py2to3_PYERR_SIMPLE_STRING_FMTCHR "'"
            " attribute of a '%.50s' object.",
        Py2to3_PYERR_PREPARE_SIMPLE_STRING( name ),
        Py_TYPE(obj)->tp_name
    );
    return -1;
}

/*-----------------------------------------------------------------------------
|  Raise an attempt to delete read-only attribute error:
+----------------------------------------------------------------------------*/

static int
delete_readonly_error ( has_traits_object * obj, PyObject * name ) {

    if ( !Py2to3_SimpleString_Check( name ) ) {
        return invalid_attribute_error();
    }

    PyErr_Format(
        TraitError,
        "Cannot delete the read only '%.400" Py2to3_PYERR_SIMPLE_STRING_FMTCHR "'"
            " attribute of a '%.50s' object.",
        Py2to3_PYERR_PREPARE_SIMPLE_STRING( name ),
        Py_TYPE(obj)->tp_name
    );
    return -1;
}

/*-----------------------------------------------------------------------------
|  Raise an attempt to set a read-only attribute error:
+----------------------------------------------------------------------------*/

static int
set_readonly_error ( has_traits_object * obj, PyObject * name ) {

    if ( !Py2to3_SimpleString_Check( name ) ) {
        return invalid_attribute_error();
    }

    PyErr_Format(
        TraitError,
        "Cannot modify the read only '%.400" Py2to3_PYERR_SIMPLE_STRING_FMTCHR "'"
            " attribute of a '%.50s' object.",
        Py2to3_PYERR_PREPARE_SIMPLE_STRING( name ),
        Py_TYPE(obj)->tp_name
    );
    return -1;
}

/*-----------------------------------------------------------------------------
|  Raise an attempt to set an undefined attribute error:
+----------------------------------------------------------------------------*/

static int
set_disallow_error ( has_traits_object * obj, PyObject * name ) {

    if ( !Py2to3_SimpleString_Check( name ) ) {
        return invalid_attribute_error();
    }

    PyErr_Format(
        TraitError,
        "Cannot set the undefined '%.400" Py2to3_PYERR_SIMPLE_STRING_FMTCHR "'"
            " attribute of a '%.50s' object.",
        Py2to3_PYERR_PREPARE_SIMPLE_STRING( name ),
        Py_TYPE(obj)->tp_name
    );
    return -1;
}

/*-----------------------------------------------------------------------------
|  Raise an attempt to delete a property error:
+----------------------------------------------------------------------------*/

static int
set_delete_property_error ( has_traits_object * obj, PyObject * name ) {

    if ( !Py2to3_SimpleString_Check( name ) ) {
        return invalid_attribute_error();
    }

    PyErr_Format(
        TraitError,
        "Cannot delete the '%.400" Py2to3_PYERR_SIMPLE_STRING_FMTCHR "'"
            " property of a '%.50s' object.",
        Py2to3_PYERR_PREPARE_SIMPLE_STRING( name ),
        Py_TYPE(obj)->tp_name
    );
    return -1;
}

/*-----------------------------------------------------------------------------
|  Raise an undefined attribute error:
+----------------------------------------------------------------------------*/

static void
unknown_attribute_error ( has_traits_object * obj, PyObject * name ) {

    PyErr_Format(
        PyExc_AttributeError,
        "'%.50s' object has no attribute '%.400" Py2to3_PYERR_SIMPLE_STRING_FMTCHR "'",
        Py_TYPE(obj)->tp_name,
        Py2to3_PYERR_PREPARE_SIMPLE_STRING( name )
    );
}

/*-----------------------------------------------------------------------------
|  Raise a '__dict__' must be set to a dictionary error:
+----------------------------------------------------------------------------*/

static int
dictionary_error ( void ) {

    PyErr_SetString( PyExc_TypeError,
                     "__dict__ must be set to a dictionary." );

    return -1;
}

/*-----------------------------------------------------------------------------
|  Gets/Sets a possibly NULL (or callable) value:
+----------------------------------------------------------------------------*/

static PyObject *
get_callable_value ( PyObject * value ) {
    PyObject * tuple, * temp;
    if ( value == NULL ) {
        value = Py_None;
        Py_INCREF( value );
    } else if ( PyCallable_Check( value ) ) {
        value = is_callable;
        Py_INCREF( value );
    } else if ( PyTuple_Check( value ) &&
              ( PyTuple_GET_SIZE( value ) >= 3 ) &&
              ( Py2to3_PyNum_AsLong( PyTuple_GET_ITEM( value, 0 ) ) == 10) ) {
        tuple = PyTuple_New( 3 );
        if ( tuple != NULL ) {
            PyTuple_SET_ITEM( tuple, 0, temp = PyTuple_GET_ITEM( value, 0 ) );
            Py_INCREF( temp );
            PyTuple_SET_ITEM( tuple, 1, temp = PyTuple_GET_ITEM( value, 1 ) );
            Py_INCREF( temp );
            PyTuple_SET_ITEM( tuple, 2, is_callable );
            Py_INCREF( is_callable );
            value = tuple;
        } else {
            value = NULL;
        }
    } else {
        Py_INCREF( value );
    }
    return value;
}

static PyObject *
get_value ( PyObject * value ) {
    if ( value == NULL )
        value = Py_None;
    Py_INCREF( value );
    return value;
}

static int
set_value ( PyObject ** field, PyObject * value ) {

    Py_INCREF( value );
    Py_XDECREF( *field );
    *field = value;
    return 0;
}

/*-----------------------------------------------------------------------------
|  Returns the result of calling a specified 'class' object with 1 argument:
+----------------------------------------------------------------------------*/

static PyObject *
call_class ( PyObject * class, trait_object * trait, has_traits_object * obj,
             PyObject * name, PyObject * value ) {

    PyObject * result;

    PyObject * args = PyTuple_New( 4 );
    if ( args == NULL )
        return NULL;
    PyTuple_SET_ITEM( args, 0, trait->handler );
    PyTuple_SET_ITEM( args, 1, (PyObject *) obj );
    PyTuple_SET_ITEM( args, 2, name );
    PyTuple_SET_ITEM( args, 3, value );
    Py_INCREF( trait->handler );
    Py_INCREF( obj );
    Py_INCREF( name );
    Py_INCREF( value );
    result = PyObject_Call( class, args, NULL );
    Py_DECREF( args );
    return result;
}

/*-----------------------------------------------------------------------------
|  Attempts to get the value of a key in a 'known to be a dictionary' object:
+----------------------------------------------------------------------------*/

static PyObject *
dict_getitem ( PyDictObject * dict, PyObject *key ) {
#if !defined(Py_LIMITED_API) && (PY_MAJOR_VERSION < 3 || PY_MINOR_VERSION < 3)
    Py_hash_t hash;
#endif

    assert( PyDict_Check( dict ) );

#if !defined(Py_LIMITED_API) && (PY_MAJOR_VERSION < 3 || PY_MINOR_VERSION < 3)
    hash = Py2to3_GetHash_wCache( key );
    if ( hash == -1 ) {
        PyErr_Clear();
        return NULL;
    }

    return (dict->ma_lookup)( dict, key, hash )->me_value;
#else
    return PyDict_GetItem((PyObject *)dict,key);
#endif
}

/*-----------------------------------------------------------------------------
|  Gets the definition of the matching prefix based trait for a specified name:
|
|  - This should always return a trait definition unless a fatal Python error
|    occurs.
|  - The bulk of the work is delegated to a Python implemented method because
|    the implementation is complicated in C and does not need to be executed
|    very often relative to other operations.
|
+----------------------------------------------------------------------------*/

static trait_object *
get_prefix_trait ( has_traits_object * obj, PyObject * name, int is_set ) {

    PyObject * trait = PyObject_CallMethod( (PyObject *) obj,
                           "__prefix_trait__", "(Oi)", name, is_set );

    if ( trait != NULL ) {
        assert( obj->ctrait_dict != NULL );
            PyDict_SetItem( (PyObject *) obj->ctrait_dict, name, trait );
        Py_DECREF( trait );

        if ( has_traits_setattro( obj, trait_added, name ) < 0 )
            return NULL;

        trait = get_trait( obj, name, 0 );
        Py_DECREF( trait );
    }

    return (trait_object *) trait;
}

/*-----------------------------------------------------------------------------
|  Assigns a special TraitValue to a specified trait attribute:
+----------------------------------------------------------------------------*/

static int
setattr_value ( trait_object      * trait,
                has_traits_object * obj,
                PyObject          * name,
                PyObject          * value ) {

    PyDictObject * dict;
    PyObject * trait_new, * result, * obj_dict;
    PyObject * trait_old = NULL;
    PyObject * value_old = NULL;

    trait_new = PyObject_CallMethod( value, "as_ctrait", "(O)", trait );
    if ( trait_new == NULL )
        goto error2;

    if ( (trait_new != Py_None) && (!PyTrait_CheckExact( trait_new )) ) {
        Py_DECREF( trait_new );
        return bad_trait_value_error();
    }

    dict = obj->itrait_dict;
    if ( (dict != NULL) &&
         ((trait_old = dict_getitem( dict, name )) != NULL) &&
         ((((trait_object *) trait_old)->flags & TRAIT_VALUE_PROPERTY) != 0) ) {
        result = PyObject_CallMethod( trait_old, "_unregister",
                                      "(OO)", obj, name );
        if ( result == NULL )
            goto error1;

        Py_DECREF( result );
    }

    if ( trait_new == Py_None ) {
        if ( trait_old != NULL ) {
            PyDict_DelItem( (PyObject *) dict, name );
        }
        goto success;
    }

    if ( dict == NULL ) {
        obj->itrait_dict = dict = (PyDictObject *) PyDict_New();
        if ( dict == NULL )
            goto error1;
    }

    if ( (((trait_object *) trait_new)->flags & TRAIT_VALUE_PROPERTY) != 0 ) {
        if ( (value_old = has_traits_getattro( obj, name )) == NULL )
            goto error1;

        obj_dict = obj->obj_dict;
        if ( obj_dict != NULL )
            PyDict_DelItem( obj_dict, name );
    }

    if ( PyDict_SetItem( (PyObject *) dict, name, trait_new ) < 0 )
        goto error0;

    if ( (((trait_object *) trait_new)->flags & TRAIT_VALUE_PROPERTY) != 0 ) {
        result = PyObject_CallMethod( trait_new, "_register",
                                      "(OO)", obj, name );
        if ( result == NULL )
            goto error0;

        Py_DECREF( result );

        if ( trait_property_changed( obj, name, value_old, NULL ) )
            goto error0;

        Py_DECREF( value_old );
    }
success:
    Py_DECREF( trait_new );
    return 0;

error0:
    Py_XDECREF( value_old );
error1:
    Py_DECREF( trait_new );
error2:
    return -1;
}

/*-----------------------------------------------------------------------------
|  Handles the 'setattr' operation on a 'CHasTraits' instance:
+----------------------------------------------------------------------------*/

static int
has_traits_setattro ( has_traits_object * obj,
                      PyObject          * name,
                      PyObject          * value ) {

    trait_object * trait;

    if ( (obj->itrait_dict == NULL) ||
         ((trait = (trait_object *) dict_getitem( obj->itrait_dict, name )) ==
           NULL) ) {
        trait = (trait_object *) dict_getitem( obj->ctrait_dict, name );
        if ( (trait == NULL) &&
             ((trait = get_prefix_trait( obj, name, 1 )) == NULL) )
            return -1;
    }

    if ( ((trait->flags & TRAIT_VALUE_ALLOWED) != 0) &&
          (PyObject_IsInstance( value, TraitValue ) > 0) ) {
        return setattr_value( trait, obj, name, value );
    }

    return trait->setattr( trait, trait, obj, name, value );
}

/*-----------------------------------------------------------------------------
|  Allocates a CTrait instance:
+----------------------------------------------------------------------------*/

PyObject *
has_traits_new ( PyTypeObject * type, PyObject * args, PyObject * kwds ) {

    // Call PyBaseObject_Type.tp_new to do the actual construction.
    // This allows things like ABCMeta machinery to work correctly
    // which is implemented at the C level.
    has_traits_object * obj = (has_traits_object *) PyBaseObject_Type.tp_new(type, empty_tuple, empty_dict);
    if ( obj != NULL ) {
        if (type->tp_dict == NULL) {
            PyErr_SetString(PyExc_RuntimeError, "No tp_dict");
            return NULL;
        }
        obj->ctrait_dict = (PyDictObject *) PyDict_GetItem( type->tp_dict,
                                                            class_traits );
        if (obj->ctrait_dict == NULL) {
            PyErr_SetString(PyExc_RuntimeError, "No ctrait_dict");
            return NULL;
        }
        if (!PyDict_Check( (PyObject *) obj->ctrait_dict ) ) {
            PyErr_SetString(PyExc_RuntimeError, "ctrait_dict not a dict");
            return NULL;
        }
        Py_INCREF( obj->ctrait_dict );
    }

    return (PyObject *) obj;
}

int
has_traits_init ( PyObject * obj, PyObject * args, PyObject * kwds ) {

    PyObject * key;
    PyObject * value;
    PyObject * klass;
    PyObject * handler;
    PyObject * handler_args;
    int n;
    int has_listeners;
    Py_ssize_t i = 0;

    /* Make sure no non-keyword arguments were specified: */
    if ( !PyArg_ParseTuple( args, "" ) )
        return -1;

    /* Make sure all of the object's listeners have been set up: */
    has_listeners = (PyMapping_Size( PyDict_GetItem( obj->ob_type->tp_dict,
                                     listener_traits ) ) > 0);
    if ( has_listeners ) {
        value = PyObject_CallMethod( obj, "_init_trait_listeners", "()" );
        if ( value == NULL )
            return -1;

        Py_DECREF( value );
    }

    /* Set any traits specified in the constructor: */
    if ( kwds != NULL ) {
        while ( PyDict_Next( kwds, &i, &key, &value ) ) {
            if ( has_traits_setattro( (has_traits_object *) obj, key, value )
                 == -1 )
                return -1;
        }
    }

    /* Make sure all post constructor argument assignment listeners have been
       set up: */
    if ( has_listeners ) {
        value = PyObject_CallMethod( obj, "_post_init_trait_listeners", "()" );
        if ( value == NULL )
            return -1;

        Py_DECREF( value );
    }

    /* Notify any interested monitors that a new object has been created: */
    for ( i = 0, n = PyList_GET_SIZE( _HasTraits_monitors ); i < n; i++ ) {
        value = PyList_GET_ITEM( _HasTraits_monitors, i );
        assert( PyTuple_Check( value ) );
        assert( PyTuple_GET_SIZE( value ) == 2 );

        klass   = PyTuple_GET_ITEM( value, 0 );
        handler = PyTuple_GET_ITEM( value, 1 );

        if ( PyObject_IsInstance( obj, klass ) > 0 ) {
            handler_args = PyTuple_New( 1 );
            PyTuple_SetItem( handler_args, 0, obj );
            Py_INCREF( obj );
            PyObject_Call( handler, handler_args, NULL );
            Py_DECREF( handler_args );
        }
    }

    /* Call the 'traits_init' method to finish up initialization: */
    value = PyObject_CallMethod( obj, "traits_init", "()" );
    if ( value == NULL )
        return -1;

    Py_DECREF( value );

    /* Indicate that the object has finished being initialized: */
    ((has_traits_object *) obj)->flags |= HASTRAITS_INITED;

    return 0;
}

/*-----------------------------------------------------------------------------
|  Object clearing method:
+----------------------------------------------------------------------------*/

static int
has_traits_clear ( has_traits_object * obj ) {

    Py_CLEAR( obj->ctrait_dict );
    Py_CLEAR( obj->itrait_dict );
    Py_CLEAR( obj->notifiers );
    Py_CLEAR( obj->obj_dict );

    return 0;
}

/*-----------------------------------------------------------------------------
|  Deallocates an unused 'CHasTraits' instance:
+----------------------------------------------------------------------------*/

static void
has_traits_dealloc ( has_traits_object * obj ) {

    PyObject_GC_UnTrack(obj);
    Py_TRASHCAN_SAFE_BEGIN(obj);
    has_traits_clear( obj );
    Py_TYPE(obj)->tp_free( (PyObject *) obj );
    Py_TRASHCAN_SAFE_END(obj);
}

/*-----------------------------------------------------------------------------
|  Garbage collector traversal method:
+----------------------------------------------------------------------------*/

static int
has_traits_traverse ( has_traits_object * obj, visitproc visit, void * arg ) {

    Py_VISIT( obj->ctrait_dict );
    Py_VISIT( obj->itrait_dict );
    Py_VISIT( obj->notifiers );
    Py_VISIT( obj->obj_dict );

        return 0;
}

/*-----------------------------------------------------------------------------
|  Handles the 'getattr' operation on a 'CHasTraits' instance:
+----------------------------------------------------------------------------*/

static PyObject *
has_traits_getattro ( has_traits_object * obj, PyObject * name ) {

    trait_object * trait;
    PyObject *value;
    PyObject *bad_attr_marker;
    /* The following is a performance hack to short-circuit the normal
       look-up when the value is in the object's dictionary.
*/
    PyDictObject * dict = (PyDictObject *) obj->obj_dict;

    if ( dict != NULL ) {
        assert( PyDict_Check( dict ) );

        bad_attr_marker = name;
        value = Py2to3_GetAttrDictValue(dict, name, bad_attr_marker);
        // there is a slight performance-hit here:
        // Py2to3_GetAttrDictValue cannot signal invalid attributes
        // unambiguously, so we have to reckeck in case the marker value is
        // returned. Make sure to pick an unlikely marker value.
        if((value==bad_attr_marker) && !Py2to3_AttrNameCheck(name)) {
            invalid_attribute_error();
            return NULL;
        }
        if( value != NULL ){
            Py_INCREF( value );
            return value;
        }
    }
    /* End of performance hack */

    if ( ((obj->itrait_dict != NULL) &&
         ((trait = (trait_object *) dict_getitem( obj->itrait_dict, name )) !=
          NULL)) ||
         ((trait = (trait_object *) dict_getitem( obj->ctrait_dict, name )) !=
          NULL) )
    {
        return trait->getattr( trait, obj, name );
    }

    if ( (value = PyObject_GenericGetAttr( (PyObject *) obj, name )) != NULL )
        return value;

    PyErr_Clear();

    if ( (trait = get_prefix_trait( obj, name, 0 )) != NULL )
        return trait->getattr( trait, obj, name );

    return NULL;
}


/*-----------------------------------------------------------------------------
|  Returns (and optionally creates) a specified instance or class trait:
+----------------------------------------------------------------------------*/

static PyObject *
get_trait ( has_traits_object * obj, PyObject * name, int instance ) {

    int i, n;
    PyDictObject * itrait_dict;
    trait_object * trait;
    trait_object * itrait;
    PyListObject * notifiers;
    PyListObject * inotifiers;
    PyObject     * item;

    /* If there already is an instance specific version of the requested trait,
       then return it: */
    itrait_dict = obj->itrait_dict;
    if ( itrait_dict != NULL ) {
        trait = (trait_object *) dict_getitem( itrait_dict, name );
        if ( trait != NULL ) {
            assert( PyTrait_CheckExact( trait ) );
            Py_INCREF( trait );
            return (PyObject *) trait;
        }
    }

    /* If only an instance trait can be returned (but not created), then
       return None: */
    if ( instance == 1 ) {
        Py_INCREF( Py_None );
        return Py_None;
    }

    /* Otherwise, get the class specific version of the trait (creating a
       trait class version if necessary): */
    assert( obj->ctrait_dict != NULL );
    trait = (trait_object *) dict_getitem( obj->ctrait_dict, name );
    if ( trait == NULL ) {
        if ( instance == 0 ) {
            Py_INCREF( Py_None );
            return Py_None;
        }
        if ( (trait = get_prefix_trait( obj, name, 0 )) == NULL )
            return NULL;
    }

    assert( PyTrait_CheckExact( trait ) );

    /* If an instance specific trait is not needed, return the class trait: */
    if ( instance <= 0 ) {
        Py_INCREF( trait );
        return (PyObject *) trait;
    }

    /* Otherwise, create an instance trait dictionary if it does not exist: */
    if ( itrait_dict == NULL ) {
                obj->itrait_dict = itrait_dict = (PyDictObject *) PyDict_New();
                if ( itrait_dict == NULL )
            return NULL;
    }

    /* Create a new instance trait and clone the class trait into it: */
    itrait = (trait_object *) PyType_GenericAlloc( ctrait_type, 0 );
    trait_clone( itrait, trait );
    itrait->obj_dict = trait->obj_dict;
    Py_XINCREF( itrait->obj_dict );

    /* Copy the class trait's notifier list into the instance trait: */
    if ( (notifiers = trait->notifiers) != NULL ) {
        n = PyList_GET_SIZE( notifiers );
        itrait->notifiers = inotifiers = (PyListObject *) PyList_New( n );
        if ( inotifiers == NULL )
            return NULL;

        for ( i = 0; i < n; i++ ) {
            item = PyList_GET_ITEM( notifiers, i );
            PyList_SET_ITEM( inotifiers, i, item );
            Py_INCREF( item );
        }
    }

    /* Add the instance trait to the instance's trait dictionary and return
       the instance trait if successful: */
    if ( PyDict_SetItem( (PyObject *) itrait_dict, name,
                         (PyObject *) itrait ) >= 0 )
        return (PyObject *) itrait;

    /* Otherwise, indicate that an error ocurred updating the dictionary: */
    return NULL;
}

/*-----------------------------------------------------------------------------
|  Returns (and optionally creates) a specified instance or class trait:
|
|  The legal values for 'instance' are:
|     2: Return instance trait (force creation if it does not exist)
|     1: Return existing instance trait (do not create)
|     0: Return existing instance or class trait (do not create)
|    -1: Return instance trait or force create class trait (i.e. prefix trait)
|    -2: Return the base trait (after all delegation has been resolved)
+----------------------------------------------------------------------------*/

static PyObject *
_has_traits_trait ( has_traits_object * obj, PyObject * args ) {

    has_traits_object * delegate;
    has_traits_object * temp_delegate;
    trait_object      * trait;
    PyObject          * name;
    PyObject          * daname;
    PyObject          * daname2;
    PyObject          * dict;
    int i, instance;

    /* Parse arguments, which specify the trait name and whether or not an
       instance specific version of the trait is needed or not: */
        if ( !PyArg_ParseTuple( args, "Oi", &name, &instance ) )
        return NULL;

    trait = (trait_object *) get_trait( obj, name, instance );
    if ( (instance >= -1) || (trait == NULL) )
        return (PyObject *) trait;

    /* Follow the delegation chain until we find a non-delegated trait: */
    delegate = obj;
    Py_INCREF( delegate );

    daname = name;
    Py_INCREF( daname );
    for ( i = 0; ; ) {

        if ( trait->delegate_attr_name == NULL ) {
            Py_DECREF( delegate );
            Py_DECREF( daname );
            return (PyObject *) trait;
        }

        dict = delegate->obj_dict;

        temp_delegate = NULL;
        if (dict != NULL) {
            temp_delegate = (has_traits_object *) PyDict_GetItem(
                dict, trait->delegate_name );
            if (temp_delegate == NULL) {
                PyErr_Clear();
            }
            else {
                /* PyDict_GetItem returns a borrowed reference,
                   so we need to INCREF. */
                Py_INCREF( temp_delegate );
            }
        }
        if (temp_delegate == NULL) {
            /* has_traits_getattro returns a new reference,
               so no need to INCREF. */
            temp_delegate = (has_traits_object *) has_traits_getattro(
                delegate, trait->delegate_name );
        }
        if (temp_delegate == NULL) {
            break;
        }
        Py_DECREF( delegate );
        delegate = temp_delegate;

        if ( !PyHasTraits_Check( delegate ) ) {
            bad_delegate_error2( obj, name );
            break;
        }

        daname2 = trait->delegate_attr_name( trait, obj, daname );
        Py_DECREF( daname );
        daname = daname2;
        Py_DECREF( trait );
        if ( ((delegate->itrait_dict == NULL) ||
              ((trait = (trait_object *) dict_getitem( delegate->itrait_dict,
                      daname )) == NULL)) &&
             ((trait = (trait_object *) dict_getitem( delegate->ctrait_dict,
                      daname )) == NULL) &&
             ((trait = get_prefix_trait( delegate, daname2, 0 )) == NULL) ) {
            bad_delegate_error( obj, name );
            break;
        }

        if ( Py_TYPE(trait) != ctrait_type ) {
            fatal_trait_error();
            break;
        }

        if ( ++i >= 100 ) {
            delegation_recursion_error2( obj, name );
            break;
        }

        Py_INCREF( trait );
    }
    Py_DECREF( delegate );
    Py_DECREF( daname );

    return NULL;
}

/*-----------------------------------------------------------------------------
|  Calls notifiers when a trait 'property' is explicitly changed:
+----------------------------------------------------------------------------*/

static int
trait_property_changed ( has_traits_object * obj, PyObject * name,
                         PyObject * old_value, PyObject * new_value ) {

    trait_object * trait;
    PyListObject * tnotifiers;
    PyListObject * onotifiers;
    int null_new_value;
    int rc = 0;

    if ( (trait = (trait_object *) get_trait( obj, name, -1 )) == NULL )
        return -1;

    tnotifiers = trait->notifiers;
    onotifiers = obj->notifiers;
    Py_DECREF( trait );

    if ( has_notifiers( tnotifiers, onotifiers ) ) {

        null_new_value = (new_value == NULL);
        if ( null_new_value ) {
           new_value = has_traits_getattro( obj, name );
           if ( new_value == NULL )
               return -1;
        }

        rc = call_notifiers( tnotifiers, onotifiers, obj, name,
                             old_value, new_value );

        if ( null_new_value ) {
            Py_DECREF( new_value );
        }
    }

    return rc;
}

/*-----------------------------------------------------------------------------
|  Calls notifiers when a trait 'property' is explicitly changed:
+----------------------------------------------------------------------------*/

static PyObject *
_has_traits_property_changed ( has_traits_object * obj, PyObject * args ) {

    PyObject * name, * old_value;
    PyObject * new_value = NULL;

    /* Parse arguments, which specify the name of the changed trait, the
       previous value, and the new value: */
        if ( !PyArg_ParseTuple( args, "OO|O", &name, &old_value, &new_value ) )
        return NULL;

    if ( trait_property_changed( obj, name, old_value, new_value ) )
        return NULL;

    Py_INCREF( Py_None );
    return Py_None;
}

/*-----------------------------------------------------------------------------
|  Handles firing a traits 'xxx_items' event:
+----------------------------------------------------------------------------*/

static PyObject *
_has_traits_items_event ( has_traits_object * obj, PyObject * args ) {

    PyObject * name;
    PyObject * event_object;
    PyObject * event_trait;
    PyObject * result;
    trait_object * trait;
    int can_retry = 1;

        if ( !PyArg_ParseTuple( args, "OOO", &name, &event_object, &event_trait ) )
        return NULL;

    if ( !PyTrait_CheckExact( event_trait ) ) {
        bad_trait_value_error();
        return NULL;
    }

    if ( !Py2to3_AttrNameCheck( name ) ) {
        invalid_attribute_error();
        return NULL;
    }
retry:
    if ( ((obj->itrait_dict == NULL) ||
          ((trait = (trait_object *) dict_getitem( obj->itrait_dict, name )) ==
            NULL)) &&
          ((trait = (trait_object *) dict_getitem( obj->ctrait_dict, name )) ==
            NULL) ) {
add_trait:
        if ( !can_retry )
            return cant_set_items_error();

        result = PyObject_CallMethod( (PyObject *) obj, "add_trait",
                                      "(OO)", name, event_trait );
        if ( result == NULL )
            return NULL;

        Py_DECREF( result );
        can_retry = 0;
        goto retry;
    }

    if ( trait->setattr == setattr_disallow )
        goto add_trait;

    if ( trait->setattr( trait, trait, obj, name, event_object ) < 0 )
        return NULL;

    Py_INCREF( Py_None );

    return Py_None;
}

/*-----------------------------------------------------------------------------
|  Enables/Disables trait change notification for the object:
+----------------------------------------------------------------------------*/

static PyObject *
_has_traits_change_notify ( has_traits_object * obj, PyObject * args ) {

    int enabled;

    /* Parse arguments, which specify the new trait notification
       enabled/disabled state: */
        if ( !PyArg_ParseTuple( args, "i", &enabled ) )
        return NULL;

    if ( enabled ) {
        obj->flags &= (~HASTRAITS_NO_NOTIFY);
    } else {
        obj->flags |= HASTRAITS_NO_NOTIFY;
    }

    Py_INCREF( Py_None );
    return Py_None;
}

/*-----------------------------------------------------------------------------
|  Enables/Disables trait change notifications when this object is assigned to
|  a trait:
+----------------------------------------------------------------------------*/

static PyObject *
_has_traits_veto_notify ( has_traits_object * obj, PyObject * args ) {

    int enabled;

    /* Parse arguments, which specify the new trait notification veto
       enabled/disabled state: */
        if ( !PyArg_ParseTuple( args, "i", &enabled ) )
        return NULL;

    if ( enabled ) {
        obj->flags |= HASTRAITS_VETO_NOTIFY;
    } else {
        obj->flags &= (~HASTRAITS_VETO_NOTIFY);
    }

    Py_INCREF( Py_None );
    return Py_None;
}

/*-----------------------------------------------------------------------------
|  This method is called at the end of a HasTraits constructor and the
|  __setstate__ method to perform any final object initialization needed.
+----------------------------------------------------------------------------*/

static PyObject *
_has_traits_init ( has_traits_object * obj ) {

    Py_INCREF( Py_None );
    return Py_None;
}

/*-----------------------------------------------------------------------------
|  Returns whether or not the object has finished being initialized:
+----------------------------------------------------------------------------*/

static PyObject *
_has_traits_inited ( has_traits_object * obj, PyObject * args ) {

    int traits_inited = -1;

        if ( !PyArg_ParseTuple( args, "|i", &traits_inited ) )
        return NULL;

    if ( traits_inited > 0 )
        obj->flags |= HASTRAITS_INITED;

    if ( obj->flags & HASTRAITS_INITED ) {
        Py_INCREF( Py_True );
        return Py_True;
    }
    Py_INCREF( Py_False );
    return Py_False;
}

/*-----------------------------------------------------------------------------
|  Returns the instance trait dictionary:
+----------------------------------------------------------------------------*/

static PyObject *
_has_traits_instance_traits ( has_traits_object * obj, PyObject * args ) {

        if ( !PyArg_ParseTuple( args, "" ) )
        return NULL;

    if ( obj->itrait_dict == NULL )
                obj->itrait_dict = (PyDictObject *) PyDict_New();

    Py_XINCREF( obj->itrait_dict );

    return (PyObject *) obj->itrait_dict;
}

/*-----------------------------------------------------------------------------
|  Returns (and optionally creates) the anytrait 'notifiers' list:
+----------------------------------------------------------------------------*/

static PyObject *
_has_traits_notifiers ( has_traits_object * obj, PyObject * args ) {

    PyObject * result;
    PyObject * list;
    int force_create;

    if ( !PyArg_ParseTuple( args, "i", &force_create ) )
        return NULL;

    result = (PyObject *) obj->notifiers;
    if ( result == NULL ) {
        if ( force_create ) {
            list = PyList_New(0);
            if (list == NULL)
                return NULL;
            obj->notifiers = (PyListObject *)list;
            result = list;
        }
        else {
            result = Py_None;
        }
    }
    Py_INCREF( result );
    return result;
}

/*-----------------------------------------------------------------------------
|  Returns the object's instance dictionary:
+----------------------------------------------------------------------------*/

static PyObject *
get_has_traits_dict ( has_traits_object * obj, void * closure ) {

    PyObject * obj_dict = obj->obj_dict;
    if ( obj_dict == NULL ) {
        obj->obj_dict = obj_dict = PyDict_New();
        if ( obj_dict == NULL )
            return NULL;
    }
    Py_INCREF( obj_dict );

    return obj_dict;
}

/*-----------------------------------------------------------------------------
|  Sets the object's dictionary:
+----------------------------------------------------------------------------*/

static int
set_has_traits_dict ( has_traits_object * obj, PyObject * value,
                      void * closure ) {

    if ( !PyDict_Check( value ) )
        return dictionary_error();

    return set_value( &obj->obj_dict, value );
}

/*-----------------------------------------------------------------------------
|  'CHasTraits' instance methods:
+----------------------------------------------------------------------------*/

static PyMethodDef has_traits_methods[] = {
        { "trait_property_changed", (PyCFunction) _has_traits_property_changed,
      METH_VARARGS,
      PyDoc_STR( "trait_property_changed(name,old_value[,new_value])" ) },
        { "trait_items_event", (PyCFunction) _has_traits_items_event, METH_VARARGS,
      PyDoc_STR( "trait_items_event(event_trait,name,items_event)" ) },
        { "_trait_change_notify", (PyCFunction) _has_traits_change_notify,
      METH_VARARGS,
      PyDoc_STR( "_trait_change_notify(boolean)" ) },
        { "_trait_veto_notify", (PyCFunction) _has_traits_veto_notify,
      METH_VARARGS,
      PyDoc_STR( "_trait_veto_notify(boolean)" ) },
        { "traits_init", (PyCFunction) _has_traits_init,
      METH_NOARGS,
      PyDoc_STR( "traits_init()" ) },
        { "traits_inited", (PyCFunction) _has_traits_inited,       METH_VARARGS,
      PyDoc_STR( "traits_inited([True])" ) },
        { "_trait",           (PyCFunction) _has_traits_trait,     METH_VARARGS,
      PyDoc_STR( "_trait(name,instance) -> trait" ) },
        { "_instance_traits", (PyCFunction) _has_traits_instance_traits,
      METH_VARARGS,
      PyDoc_STR( "_instance_traits() -> dict" ) },
        { "_notifiers",       (PyCFunction) _has_traits_notifiers, METH_VARARGS,
      PyDoc_STR( "_notifiers(force_create) -> list" ) },
        { NULL, NULL },
};

/*-----------------------------------------------------------------------------
|  'CHasTraits' property definitions:
+----------------------------------------------------------------------------*/

static PyGetSetDef has_traits_properties[] = {
        { "__dict__",  (getter) get_has_traits_dict,
                   (setter) set_has_traits_dict },
        { 0 }
};

/*-----------------------------------------------------------------------------
|  'CHasTraits' type definition:
+----------------------------------------------------------------------------*/

static PyTypeObject has_traits_type = {
        PyVarObject_HEAD_INIT( DEFERRED_ADDRESS( &PyType_Type ), 0)
        "traits.ctraits.CHasTraits",
        sizeof( has_traits_object ),
        0,
        (destructor) has_traits_dealloc,                    /* tp_dealloc */
        0,                                                  /* tp_print */
        0,                                                  /* tp_getattr */
        0,                                                  /* tp_setattr */
        0,                                                  /* tp_compare */
        0,                                                  /* tp_repr */
        0,                                                  /* tp_as_number */
        0,                                                  /* tp_as_sequence */
        0,                                                  /* tp_as_mapping */
        0,                                                  /* tp_hash */
        0,                                                  /* tp_call */
        0,                                                  /* tp_str */
        (getattrofunc) has_traits_getattro,                 /* tp_getattro */
        (setattrofunc) has_traits_setattro,                 /* tp_setattro */
        0,                                                                      /* tp_as_buffer */
        Py_TPFLAGS_DEFAULT | Py_TPFLAGS_BASETYPE | Py_TPFLAGS_HAVE_GC,/* tp_flags */
        0,                                                  /* tp_doc */
        (traverseproc) has_traits_traverse,                 /* tp_traverse */
        (inquiry) has_traits_clear,                         /* tp_clear */
        0,                                                  /* tp_richcompare */
        0,                                                  /* tp_weaklistoffset */
        0,                                                  /* tp_iter */
        0,                                                  /* tp_iternext */
        has_traits_methods,                                 /* tp_methods */
        0,                                                  /* tp_members */
        has_traits_properties,                              /* tp_getset */
        DEFERRED_ADDRESS( &PyBaseObject_Type ),             /* tp_base */
        0,                                                                      /* tp_dict */
        0,                                                                      /* tp_descr_get */
        0,                                                                      /* tp_descr_set */
        sizeof( has_traits_object ) - sizeof( PyObject * ), /* tp_dictoffset */
        has_traits_init,                                    /* tp_init */
        DEFERRED_ADDRESS( PyType_GenericAlloc ),            /* tp_alloc */
        has_traits_new                                      /* tp_new */
};

/*-----------------------------------------------------------------------------
|  Returns the default value associated with a specified trait:
+----------------------------------------------------------------------------*/

static PyObject *
default_value_for ( trait_object      * trait,
                    has_traits_object * obj,
                    PyObject          * name ) {

    PyObject * result = NULL, * value, * dv, * kw, * tuple;

    switch ( trait->default_value_type ) {
        case 0:
        case 1:
            result = trait->default_value;
            Py_INCREF( result );
            break;
        case 2:
            result = (PyObject *) obj;
            Py_INCREF( obj );
            break;
        case 3:
            return PySequence_List( trait->default_value );
        case 4:
            return PyDict_Copy( trait->default_value );
        case 5:
            return call_class( TraitListObject, trait, obj, name,
                               trait->default_value );
        case 6:
            return call_class( TraitDictObject, trait, obj, name,
                               trait->default_value );
        case 7:
            dv = trait->default_value;
            kw = PyTuple_GET_ITEM( dv, 2 );
            if ( kw == Py_None )
                kw = NULL;
            return PyObject_Call( PyTuple_GET_ITEM( dv, 0 ),
                                  PyTuple_GET_ITEM( dv, 1 ), kw );
        case 8:
            if ( (tuple = PyTuple_New( 1 )) == NULL )
                return NULL;
            PyTuple_SET_ITEM( tuple, 0, (PyObject *) obj );
            Py_INCREF( obj );
            result = PyObject_Call( trait->default_value, tuple, NULL );
            Py_DECREF( tuple );
            if ( (result != NULL) && (trait->validate != NULL) ) {
                value = trait->validate( trait, obj, name, result );
                Py_DECREF( result );
                return value;
            }
            break;
        case 9:
            return call_class( TraitSetObject, trait, obj, name,
                               trait->default_value );
    }
    return result;
}

/*-----------------------------------------------------------------------------
|  Returns the value assigned to a standard Python attribute:
+----------------------------------------------------------------------------*/

static PyObject *
getattr_python ( trait_object      * trait,
                 has_traits_object * obj,
                 PyObject          * name ) {

    return PyObject_GenericGetAttr( (PyObject *) obj, name );
}

/*-----------------------------------------------------------------------------
|  Returns the value assigned to a generic Python attribute:
+----------------------------------------------------------------------------*/

static PyObject *
getattr_generic ( trait_object      * trait,
                  has_traits_object * obj,
                  PyObject          * name ) {

    return PyObject_GenericGetAttr( (PyObject *) obj, name );
}

/*-----------------------------------------------------------------------------
|  Returns the value assigned to an event trait:
+----------------------------------------------------------------------------*/

static PyObject *
getattr_event ( trait_object      * trait,
                has_traits_object * obj,
                PyObject          * name ) {

    PyErr_Format( PyExc_AttributeError,
        "The %.400" Py2to3_PYERR_SIMPLE_STRING_FMTCHR
            " trait of a %.50s instance is an 'event', which is write only.",
        Py2to3_PYERR_PREPARE_SIMPLE_STRING( name ), Py_TYPE(obj)->tp_name );

    return NULL;
}

/*-----------------------------------------------------------------------------
|  Returns the value assigned to a standard trait:
+----------------------------------------------------------------------------*/

static PyObject *
getattr_trait ( trait_object      * trait,
                has_traits_object * obj,
                PyObject          * name ) {

    int rc;
    PyListObject * tnotifiers;
    PyListObject * onotifiers;
    PyObject * result;
    PyObject * nname;
    PyObject * dict = obj->obj_dict;

    if ( dict == NULL ) {
        dict = PyDict_New();
        if ( dict == NULL )
            return NULL;

        obj->obj_dict = dict;
        }

        if ( Py2to3_SimpleString_Check( name ) ) {
        if ( (result = default_value_for( trait, obj, name )) != NULL ) {
            if ( PyDict_SetItem( dict, name, result ) >= 0 ) {

                rc = 0;
                if ( (trait->post_setattr != NULL) &&
                     ((trait->flags & TRAIT_IS_MAPPED) == 0) )
                    rc = trait->post_setattr( trait, obj, name, result );

                if (rc == 0) {
                    tnotifiers = trait->notifiers;
                    onotifiers = obj->notifiers;
                    if ( has_notifiers( tnotifiers, onotifiers ) )
                        rc = call_notifiers( tnotifiers, onotifiers, obj, name,
                                             Uninitialized, result );
                }
                if ( rc == 0 )
                    return result;
            }
            Py_DECREF( result );
        }

        return NULL;
    }

    nname = Py2to3_NormaliseAttrName(name);

    if( nname == NULL ){
        invalid_attribute_error();
        return NULL;
    }

    if ( (result = default_value_for( trait, obj, nname )) != NULL ) {
        if ( PyDict_SetItem( dict, nname, result ) >= 0 ) {

            rc = 0;
            if ( (trait->post_setattr != NULL) &&
                 ((trait->flags & TRAIT_IS_MAPPED) == 0) )
                rc = trait->post_setattr( trait, obj, nname, result );

            if (rc == 0) {
                tnotifiers = trait->notifiers;
                onotifiers = obj->notifiers;
                if ( has_notifiers( tnotifiers, onotifiers ) )
                    rc = call_notifiers( tnotifiers, onotifiers, obj, nname,
                                         Uninitialized, result );
            }
            if ( rc == 0 ){
                Py2to3_FinishNormaliseAttrName(name,nname);
                return result;
            }
        }
        Py_DECREF( result );
    }

    if ( PyErr_ExceptionMatches( PyExc_KeyError ) )
        PyErr_SetObject( PyExc_AttributeError, nname );

    Py2to3_FinishNormaliseAttrName(name,nname);
    Py_DECREF( name );
    return NULL;
}

/*-----------------------------------------------------------------------------
|  Returns the value assigned to a delegated trait:
+----------------------------------------------------------------------------*/

static PyObject *
getattr_delegate ( trait_object      * trait,
                   has_traits_object * obj,
                   PyObject          * name ) {

    PyTypeObject * tp;
    PyObject     * delegate_attr_name;
    PyObject     * delegate;
    PyObject     * result;
    PyObject     * nname;
    PyObject     * dict = obj->obj_dict;

    if ( (dict == NULL) ||
         ((delegate = PyDict_GetItem( dict, trait->delegate_name )) == NULL) ){
        // Handle the case when the delegate is not in the instance dictionary
        // (could be a method that returns the real delegate):
        delegate = has_traits_getattro( obj, trait->delegate_name );
        if ( delegate == NULL )
            return NULL;
    } else {
        Py_INCREF( delegate );
    }

    nname = Py2to3_NormaliseAttrName(name);

    if( nname == NULL ){
        invalid_attribute_error();
        Py_DECREF( delegate );
        return NULL;
    }

    delegate_attr_name = trait->delegate_attr_name( trait, obj, nname );
    tp = Py_TYPE(delegate);

    if ( tp->tp_getattro != NULL ) {
        result = (*tp->tp_getattro)( delegate, delegate_attr_name );
        goto done;
    }

    if ( tp->tp_getattr != NULL ) {
        PyObject *delegate_attr_name_c_str = Py2to3_AttrNameCStr( delegate_attr_name );
        if(delegate_attr_name_c_str == NULL){
            result = NULL;
        } else {
            result = (*tp->tp_getattr)( delegate,
                             Py2to3_AttrName_AS_STRING( delegate_attr_name_c_str ) );
            Py2to3_FinishAttrNameCStr(delegate_attr_name_c_str);
            goto done;
        }
    }

    PyErr_Format( DelegationError,
        "The '%.50s' object has no attribute '%.400"
            Py2to3_PYERR_SIMPLE_STRING_FMTCHR "'"
            " because its %.50s delegate has no attribute '%.400"
            Py2to3_PYERR_SIMPLE_STRING_FMTCHR "'.",
        Py_TYPE(obj)->tp_name,
        Py2to3_PYERR_PREPARE_SIMPLE_STRING( name ),
        tp->tp_name,
        Py2to3_PYERR_PREPARE_SIMPLE_STRING( delegate_attr_name )
    );
    result = NULL;

done:
    Py_DECREF( delegate_attr_name );
    Py2to3_FinishNormaliseAttrName(name,nname);
    Py_DECREF( delegate );
    return result;
}

/*-----------------------------------------------------------------------------
|  Raises an exception when a disallowed trait is accessed:
+----------------------------------------------------------------------------*/

static PyObject *
getattr_disallow ( trait_object      * trait,
                   has_traits_object * obj,
                   PyObject          * name ) {

    if ( Py2to3_SimpleString_Check( name ) )
        unknown_attribute_error( obj, name );
    else
        invalid_attribute_error();

    return NULL;
}

/*-----------------------------------------------------------------------------
|  Returns the value of a constant trait:
+----------------------------------------------------------------------------*/

static PyObject *
getattr_constant ( trait_object      * trait,
                   has_traits_object * obj,
                   PyObject          * name ) {

    Py_INCREF( trait->default_value );
    return trait->default_value;
}

/*-----------------------------------------------------------------------------
|  Assigns a value to a specified property trait attribute:
+----------------------------------------------------------------------------*/

static PyObject *
getattr_property0 ( trait_object      * trait,
                    has_traits_object * obj,
                    PyObject          * name ) {

    return PyObject_Call( trait->delegate_name, empty_tuple, NULL );
}

static PyObject *
getattr_property1 ( trait_object      * trait,
                    has_traits_object * obj,
                    PyObject          * name ) {

    PyObject * result;

    PyObject * args = PyTuple_New( 1 );
    if ( args == NULL )
        return NULL;

    PyTuple_SET_ITEM( args, 0, (PyObject *) obj );
    Py_INCREF( obj );
    result = PyObject_Call( trait->delegate_name, args, NULL );
    Py_DECREF( args );

    return result;
}

static PyObject *
getattr_property2 ( trait_object      * trait,
                    has_traits_object * obj,
                    PyObject          * name ) {

    PyObject * result;

    PyObject * args = PyTuple_New( 2 );
    if ( args == NULL )
        return NULL;

    PyTuple_SET_ITEM( args, 0, (PyObject *) obj );
    Py_INCREF( obj );
    PyTuple_SET_ITEM( args, 1, name );
    Py_INCREF( name );
    result = PyObject_Call( trait->delegate_name, args, NULL );
    Py_DECREF( args );

    return result;
}

static PyObject *
getattr_property3 ( trait_object      * trait,
                    has_traits_object * obj,
                    PyObject          * name ) {

    PyObject * result;

    PyObject * args = PyTuple_New( 3 );
    if ( args == NULL )
        return NULL;

    PyTuple_SET_ITEM( args, 0, (PyObject *) obj );
    Py_INCREF( obj );
    PyTuple_SET_ITEM( args, 1, name );
    Py_INCREF( name );
    PyTuple_SET_ITEM( args, 2, (PyObject *) trait );
    Py_INCREF( trait );
    result = PyObject_Call( trait->delegate_name, args, NULL );
    Py_DECREF( args );

    return result;
}

static trait_getattr getattr_property_handlers[] = {
    getattr_property0, getattr_property1, getattr_property2, getattr_property3
};

/*-----------------------------------------------------------------------------
|  Assigns a value to a specified standard Python attribute:
+----------------------------------------------------------------------------*/

static int
setattr_python ( trait_object      * traito,
                 trait_object      * traitd,
                 has_traits_object * obj,
                 PyObject          * name,
                 PyObject          * value ) {

    PyObject *nname;
    PyObject * dict = obj->obj_dict;

    if ( value != NULL ) {
        if ( dict == NULL ) {
            dict = PyDict_New();
            if ( dict == NULL )
                return -1;
                obj->obj_dict = dict;
        }

        nname = Py2to3_NormaliseAttrName( name );
        if( nname == NULL )
            return invalid_attribute_error();

        if ( PyDict_SetItem( dict, nname, value ) >= 0 ){
            Py2to3_FinishNormaliseAttrName(name,nname);
            return 0;
        }
        if ( PyErr_ExceptionMatches( PyExc_KeyError ) )
            PyErr_SetObject( PyExc_AttributeError, nname );

        Py2to3_FinishNormaliseAttrName(name,nname);
        return -1;
    }

    if ( dict != NULL ) {
        PyObject *nname = Py2to3_NormaliseAttrName( name );
        if( nname == NULL )
            return invalid_attribute_error();

        if ( PyDict_DelItem( dict, nname ) >= 0 ){
            Py2to3_FinishNormaliseAttrName(name,nname);
            return 0;
        }

        if ( PyErr_ExceptionMatches( PyExc_KeyError ) )
            unknown_attribute_error( obj, nname );

        Py2to3_FinishNormaliseAttrName(name,nname);
        return -1;
    }

    if ( Py2to3_SimpleString_Check( name ) ) {
        unknown_attribute_error( obj, name );

        return -1;
    }

    return invalid_attribute_error();
}

/*-----------------------------------------------------------------------------
|  Assigns a value to a specified generic Python attribute:
+----------------------------------------------------------------------------*/

static int
setattr_generic ( trait_object      * traito,
                  trait_object      * traitd,
                  has_traits_object * obj,
                  PyObject          * name,
                  PyObject          * value ) {

    return PyObject_GenericSetAttr( (PyObject *) obj, name, value );
}

/*-----------------------------------------------------------------------------
|  Call all notifiers for a specified trait:
+----------------------------------------------------------------------------*/

static int
call_notifiers ( PyListObject      * tnotifiers,
                 PyListObject      * onotifiers,
                 has_traits_object * obj,
                 PyObject          * name,
                 PyObject          * old_value,
                 PyObject          * new_value ) {

    int i, n, new_value_has_traits;
    PyObject * result, * item, * temp;

    int rc = 0;

    PyObject * arg_temp  = Py_None;
    PyObject * user_args = NULL;
    PyObject * args      = PyTuple_New( 4 );
    if ( args == NULL )
        return -1;

    new_value_has_traits = PyHasTraits_Check( new_value );
    PyTuple_SET_ITEM( args, 0, (PyObject *) obj );
    PyTuple_SET_ITEM( args, 1, name );
    PyTuple_SET_ITEM( args, 2, old_value );
    PyTuple_SET_ITEM( args, 3, new_value );
    Py_INCREF( obj );
    Py_INCREF( name );
    Py_INCREF( old_value );
    Py_INCREF( new_value );

    // Do nothing if the user has explicitly requested no traits notifications
    // to be sent.
    if ( (obj->flags & HASTRAITS_NO_NOTIFY) != 0 )
       goto exit2;

    if ( _trait_notification_handler != NULL ) {
        user_args = PyTuple_New( 2 );
        if ( user_args == NULL ) {
            Py_DECREF( args );
            return -1;
        }
        PyTuple_SET_ITEM( user_args, 0, arg_temp );
        PyTuple_SET_ITEM( user_args, 1, args );
        Py_INCREF( arg_temp );
        Py_INCREF( args );
    }

    if ( tnotifiers != NULL ) {
        n    = PyList_GET_SIZE( tnotifiers );
        temp = NULL;
        if ( n > 1 ) {
            temp = PyList_New( n );
            if ( temp == NULL ) {
                rc = -1;
                goto exit2;
            }
            for ( i = 0; i < n; i++ ) {
                item = PyList_GET_ITEM( tnotifiers, i );
                PyList_SET_ITEM( temp, i, item );
                Py_INCREF( item );
            }
            tnotifiers = (PyListObject *) temp;
        }
        for ( i = 0; i < n; i++ ) {
            if ( new_value_has_traits &&
                 (((has_traits_object *) new_value)->flags &
                    HASTRAITS_VETO_NOTIFY) ) {
                goto exit;
            }
            if ( (_trait_notification_handler != NULL) && (user_args != NULL) ){
                Py_DECREF( arg_temp );
                arg_temp = PyList_GET_ITEM( tnotifiers, i );
                Py_INCREF( arg_temp );
                PyTuple_SET_ITEM( user_args, 0, arg_temp );
                result = PyObject_Call( _trait_notification_handler,
                                        user_args, NULL );
            } else {
                result = PyObject_Call( PyList_GET_ITEM( tnotifiers, i ),
                                        args, NULL );
            }
            if ( result == NULL ) {
                rc = -1;
                goto exit;
            }
            Py_DECREF( result );
        }
        Py_XDECREF( temp );
    }

    temp = NULL;
    if ( onotifiers != NULL ) {
        n = PyList_GET_SIZE( onotifiers );
        if ( n > 1 ) {
            temp = PyList_New( n );
            if ( temp == NULL ) {
                rc = -1;
                goto exit2;
            }
            for ( i = 0; i < n; i++ ) {
                item = PyList_GET_ITEM( onotifiers, i );
                PyList_SET_ITEM( temp, i, item );
                Py_INCREF( item );
            }
            onotifiers = (PyListObject *) temp;
        }
        for ( i = 0; i < n; i++ ) {
            if ( new_value_has_traits &&
                 (((has_traits_object *) new_value)->flags &
                    HASTRAITS_VETO_NOTIFY) ) {
                break;
            }
            if ( (_trait_notification_handler != NULL) && (user_args != NULL) ){
                Py_DECREF( arg_temp );
                arg_temp = PyList_GET_ITEM( onotifiers, i );
                Py_INCREF( arg_temp );
                PyTuple_SET_ITEM( user_args, 0, arg_temp );
                result = PyObject_Call( _trait_notification_handler,
                                        user_args, NULL );
            } else {
                result = PyObject_Call( PyList_GET_ITEM( onotifiers, i ),
                                        args, NULL );
            }
            if ( result == NULL ) {
                rc = -1;
                goto exit;
            }
            Py_DECREF( result );
        }
    }
exit:
    Py_XDECREF( temp );
exit2:
    Py_XDECREF( user_args );
    Py_DECREF( args );

    return rc;
}

/*-----------------------------------------------------------------------------
|  Assigns a value to a specified event trait attribute:
+----------------------------------------------------------------------------*/

static int
setattr_event ( trait_object      * traito,
                trait_object      * traitd,
                has_traits_object * obj,
                PyObject          * name,
                PyObject          * value ) {

    int rc = 0;
    PyListObject * tnotifiers;
    PyListObject * onotifiers;

    if ( value != NULL ) {
        if ( traitd->validate != NULL ) {
            value = traitd->validate( traitd, obj, name, value );
            if ( value == NULL )
                return -1;
        } else {
            Py_INCREF( value );
        }

        tnotifiers = traito->notifiers;
        onotifiers = obj->notifiers;

        if ( has_notifiers( tnotifiers, onotifiers ) )
            rc = call_notifiers( tnotifiers, onotifiers, obj, name,
                                 Undefined, value );

        Py_DECREF( value );
    }

    return rc;
}

/*-----------------------------------------------------------------------------
|  Assigns a value to a specified normal trait attribute:
+----------------------------------------------------------------------------*/

static int
setattr_trait ( trait_object      * traito,
                trait_object      * traitd,
                has_traits_object * obj,
                PyObject          * name,
                PyObject          * value ) {

    int rc;
    int changed;
    int do_notifiers;
    trait_post_setattr post_setattr;
    PyListObject * tnotifiers = NULL;
    PyListObject * onotifiers = NULL;
    PyObject     * old_value  = NULL;
    PyObject     * original_value;
    PyObject     * new_value;

    PyObject *nname;

    PyObject * dict = obj->obj_dict;


    changed = (traitd->flags & TRAIT_NO_VALUE_TEST);

    if ( value == NULL ) {
        if ( dict == NULL )
            return 0;

        nname = Py2to3_NormaliseAttrName(name);
        if( nname == NULL )
            return invalid_attribute_error();

        old_value = PyDict_GetItem( dict, nname );
        if ( old_value == NULL ) {
            Py2to3_FinishNormaliseAttrName( name, nname );
            return 0;
        }

        Py_INCREF( old_value );
        if ( PyDict_DelItem( dict, nname ) < 0 ) {
            Py_DECREF( old_value );
            Py2to3_FinishNormaliseAttrName( name, nname );
            return -1;
        }

        rc = 0;
        if ( (obj->flags & HASTRAITS_NO_NOTIFY) == 0 ) {
            tnotifiers = traito->notifiers;
            onotifiers = obj->notifiers;
            if ( (tnotifiers != NULL) || (onotifiers != NULL) ) {
                value = traito->getattr( traito, obj, nname );
                if ( value == NULL ) {
                    Py_DECREF( old_value );
                    Py2to3_FinishNormaliseAttrName( name, nname );
                    return -1;
                }

                if ( !changed ) {
                    changed = (old_value != value );
                    if ( changed &&
                         ((traitd->flags & TRAIT_OBJECT_IDENTITY) == 0) ) {
                        changed = PyObject_RichCompareBool( old_value,
                                                            value, Py_NE );
                        if ( changed == -1 ) {
                            PyErr_Clear();
                        }
                    }
                }

                if ( changed ) {
                    if ( traitd->post_setattr != NULL )
                        rc = traitd->post_setattr( traitd, obj, nname,
                                                   value );
                    if ( (rc == 0) &&
                         has_notifiers( tnotifiers, onotifiers ) )
                        rc = call_notifiers( tnotifiers, onotifiers,
                                             obj, nname, old_value, value );
                }

                Py_DECREF( value );
            }
        }
        Py_DECREF( old_value );
        Py2to3_FinishNormaliseAttrName( name, nname );
        return rc;
    }

    original_value = value;
    // If the object's value is Undefined, then do not call the validate
    // method (as the object's value has not yet been set).
    if ( ( traitd->validate != NULL ) &&
         ( value != Undefined ) ) {
        value = traitd->validate( traitd, obj, name, value );
        if ( value == NULL ) {
            return -1;
        }
    } else {
        Py_INCREF( value );
    }

    if ( dict == NULL ) {
        obj->obj_dict = dict = PyDict_New();
        if ( dict == NULL ) {
            Py_DECREF( value );
            return -1;
        }
    }



    nname = Py2to3_NormaliseAttrName(name);
    if( nname == NULL ){
        Py_DECREF( value );
        return invalid_attribute_error();
    }

    new_value    = (traitd->flags & TRAIT_SETATTR_ORIGINAL_VALUE)?
                   original_value: value;
    old_value    = NULL;

    tnotifiers    = traito->notifiers;
    onotifiers    = obj->notifiers;
    do_notifiers  = has_notifiers( tnotifiers, onotifiers );

    post_setattr = traitd->post_setattr;
    if ( (post_setattr != NULL) || do_notifiers ) {
        old_value = PyDict_GetItem( dict, nname );
        if ( old_value == NULL ) {
            if ( traitd != traito ) {
                old_value = traito->getattr( traito, obj, nname );
            } else {
                old_value = default_value_for( traitd, obj, nname );
            }
            if ( old_value == NULL ) {
                Py2to3_FinishNormaliseAttrName( name, nname );
                Py_DECREF( value );

                return -1;
            }
        } else {
            Py_INCREF( old_value );
        }

        if ( !changed ) {
            changed = (old_value != value);
            if ( changed &&
                 ((traitd->flags & TRAIT_OBJECT_IDENTITY) == 0) ) {
                changed = PyObject_RichCompareBool( old_value, value, Py_NE );
                if ( changed == -1 ) {
                    PyErr_Clear();
                }
            }
        }
    }

    if ( PyDict_SetItem( dict, nname, new_value ) < 0 ) {
        if ( PyErr_ExceptionMatches( PyExc_KeyError ) )
            PyErr_SetObject( PyExc_AttributeError, nname );
        Py_XDECREF( old_value );
        Py_DECREF( name );
        Py2to3_FinishNormaliseAttrName( name, nname );
        Py_DECREF( value );

        return -1;
    }

    rc = 0;

    if ( changed ) {
        if ( post_setattr != NULL )
            rc = post_setattr( traitd, obj, nname,
                    (traitd->flags & TRAIT_POST_SETATTR_ORIGINAL_VALUE)?
                    original_value: value );

        if ( (rc == 0) && do_notifiers )
            rc = call_notifiers( tnotifiers, onotifiers, obj, nname,
                                 old_value, new_value );
    }

    Py_XDECREF( old_value );
    Py2to3_FinishNormaliseAttrName( name, nname );
    Py_DECREF( value );

    return rc;
}

/*-----------------------------------------------------------------------------
|  Assigns a value to a specified delegate trait attribute:
+----------------------------------------------------------------------------*/

static int
setattr_delegate ( trait_object      * traito,
                   trait_object      * traitd,
                   has_traits_object * obj,
                   PyObject          * name,
                   PyObject          * value ) {

        PyObject          * dict;
    PyObject          * daname;
    PyObject          * daname2;
    PyObject          * temp;
    has_traits_object * delegate;
    has_traits_object * temp_delegate;
        int i, result;

    /* Follow the delegation chain until we find a non-delegated trait: */
    daname = name;
    Py_INCREF( daname );
    delegate = obj;
    for ( i = 0; ; ) {
        dict = delegate->obj_dict;
        if ( (dict != NULL) &&
             ((temp_delegate = (has_traits_object *) PyDict_GetItem( dict,
                                          traitd->delegate_name )) != NULL) ) {
            delegate = temp_delegate;
        } else {
            // Handle the case when the delegate is not in the instance
            // dictionary (could be a method that returns the real delegate):
            delegate = (has_traits_object *) has_traits_getattro( delegate,
                                                       traitd->delegate_name );
            if ( delegate == NULL ) {
                Py_DECREF( daname );
                return -1;
            }
            Py_DECREF( delegate );
        }

        // Verify that 'delegate' is of type 'CHasTraits':
        if ( !PyHasTraits_Check( delegate ) ) {
            Py_DECREF( daname );
            return bad_delegate_error2( obj, name );
        }

        daname2 = traitd->delegate_attr_name( traitd, obj, daname );
        Py_DECREF( daname );
        daname = daname2;
        if ( ((delegate->itrait_dict == NULL) ||
              ((traitd = (trait_object *) dict_getitem( delegate->itrait_dict,
                      daname )) == NULL)) &&
             ((traitd = (trait_object *) dict_getitem( delegate->ctrait_dict,
                      daname )) == NULL) &&
             ((traitd = get_prefix_trait( delegate, daname, 1 )) == NULL) ) {
            Py_DECREF( daname );
            return bad_delegate_error( obj, name );
        }

        if ( Py_TYPE(traitd) != ctrait_type ) {
            Py_DECREF( daname );
            return fatal_trait_error();
        }

        if ( traitd->delegate_attr_name == NULL ) {
            if ( traito->flags & TRAIT_MODIFY_DELEGATE ) {
                result = traitd->setattr( traitd, traitd, delegate, daname,
                                          value );
            } else {
                result = traitd->setattr( traito, traitd, obj, name, value );
                if ( result >= 0 ) {
                    temp = PyObject_CallMethod( (PyObject *) obj,
                               "_remove_trait_delegate_listener", "(Oi)",
                               name, value != NULL );
                    if ( temp == NULL ) {
                        result = -1;
                    } else {
                        Py_DECREF( temp );
                    }
                }
            }
            Py_DECREF( daname );

            return result;
        }

        if ( ++i >= 100 )
            return delegation_recursion_error( obj, name );
    }
}

/*-----------------------------------------------------------------------------
|  Assigns a value to a specified property trait attribute:
+----------------------------------------------------------------------------*/

static int
setattr_property0 ( trait_object      * traito,
                    trait_object      * traitd,
                    has_traits_object * obj,
                    PyObject          * name,
                    PyObject          * value ) {

    PyObject * result;

    if ( value == NULL )
        return set_delete_property_error( obj, name );

    result = PyObject_Call( traitd->delegate_prefix, empty_tuple, NULL );
    if ( result == NULL )
        return -1;

    Py_DECREF( result );
    return 0;
}

static int
setattr_property1 ( trait_object      * traito,
                    trait_object      * traitd,
                    has_traits_object * obj,
                    PyObject          * name,
                    PyObject          * value ) {

    PyObject * result;
    PyObject * args;

    if ( value == NULL )
        return set_delete_property_error( obj, name );

    args = PyTuple_New( 1 );
    if ( args == NULL )
        return -1;

    PyTuple_SET_ITEM( args, 0, value );
    Py_INCREF( value );
    result = PyObject_Call( traitd->delegate_prefix, args, NULL );
    Py_DECREF( args );
    if ( result == NULL )
        return -1;

    Py_DECREF( result );
    return 0;
}

static int
setattr_property2 ( trait_object      * traito,
                    trait_object      * traitd,
                    has_traits_object * obj,
                    PyObject          * name,
                    PyObject          * value ) {

    PyObject * result;
    PyObject * args;

    if ( value == NULL )
        return set_delete_property_error( obj, name );

    args = PyTuple_New( 2 );
    if ( args == NULL )
        return -1;

    PyTuple_SET_ITEM( args, 0, (PyObject *) obj );
    PyTuple_SET_ITEM( args, 1, value );
    Py_INCREF( obj );
    Py_INCREF( value );
    result = PyObject_Call( traitd->delegate_prefix, args, NULL );
    Py_DECREF( args );
    if ( result == NULL )
        return -1;

    Py_DECREF( result );
    return 0;
}

static int
setattr_property3 ( trait_object      * traito,
                    trait_object      * traitd,
                    has_traits_object * obj,
                    PyObject          * name,
                    PyObject          * value ) {

    PyObject * result;
    PyObject * args;

    if ( value == NULL )
        return set_delete_property_error( obj, name );

    args = PyTuple_New( 3 );
    if ( args == NULL )
        return -1;

    PyTuple_SET_ITEM( args, 0, (PyObject *) obj );
    PyTuple_SET_ITEM( args, 1, name );
    PyTuple_SET_ITEM( args, 2, value );
    Py_INCREF( obj );
    Py_INCREF( name );
    Py_INCREF( value );
    result = PyObject_Call( traitd->delegate_prefix, args, NULL );
    Py_DECREF( args );
    if ( result == NULL )
        return -1;

    Py_DECREF( result );
    return 0;
}

/*-----------------------------------------------------------------------------
|  Validates then assigns a value to a specified property trait attribute:
+----------------------------------------------------------------------------*/

static int
setattr_validate_property ( trait_object      * traito,
                            trait_object      * traitd,
                            has_traits_object * obj,
                            PyObject          * name,
                            PyObject          * value ) {

    int result;
    PyObject * validated;

    if ( value == NULL )
        return set_delete_property_error( obj, name );

    validated = traitd->validate( traitd, obj, name, value );
    if ( validated == NULL )
        return -1;
    result = ((trait_setattr) traitd->post_setattr)( traito, traitd, obj, name,
                                                             validated );
    Py_DECREF( validated );
    return result;
}

static PyObject *
setattr_validate0 ( trait_object      * trait,
                    has_traits_object * obj,
                    PyObject          * name,
                    PyObject          * value ) {

    return PyObject_Call( trait->py_validate, empty_tuple, NULL );
}

static PyObject *
setattr_validate1 ( trait_object      * trait,
                    has_traits_object * obj,
                    PyObject          * name,
                    PyObject          * value ) {

    PyObject * validated;

    PyObject * args = PyTuple_New( 1 );
    if ( args == NULL )
        return NULL;
    PyTuple_SET_ITEM( args, 0, value );
    Py_INCREF( value );
    validated = PyObject_Call( trait->py_validate, args, NULL );
    Py_DECREF( args );
    return validated;
}

static PyObject *
setattr_validate2 ( trait_object      * trait,
                    has_traits_object * obj,
                    PyObject          * name,
                    PyObject          * value ) {

    PyObject * validated;

    PyObject * args = PyTuple_New( 2 );
    if ( args == NULL )
        return NULL;
    PyTuple_SET_ITEM( args, 0, (PyObject *) obj );
    PyTuple_SET_ITEM( args, 1, value );
    Py_INCREF( obj );
    Py_INCREF( value );
    validated = PyObject_Call( trait->py_validate, args, NULL );
    Py_DECREF( args );
    return validated;
}

static PyObject *
setattr_validate3 ( trait_object      * trait,
                    has_traits_object * obj,
                    PyObject          * name,
                    PyObject          * value ) {

    PyObject * validated;

    PyObject * args = PyTuple_New( 3 );
    if ( args == NULL )
        return NULL;
    PyTuple_SET_ITEM( args, 0, (PyObject *) obj );
    PyTuple_SET_ITEM( args, 1, name );
    PyTuple_SET_ITEM( args, 2, value );
    Py_INCREF( obj );
    Py_INCREF( name );
    Py_INCREF( value );
    validated = PyObject_Call( trait->py_validate, args, NULL );
    Py_DECREF( args );
    return validated;
}

trait_validate setattr_validate_handlers[] = {
    setattr_validate0, setattr_validate1, setattr_validate2, setattr_validate3
};

/*-----------------------------------------------------------------------------
|  Raises an exception when attempting to assign to a disallowed trait:
+----------------------------------------------------------------------------*/

static int
setattr_disallow ( trait_object      * traito,
                   trait_object      * traitd,
                   has_traits_object * obj,
                   PyObject          * name,
                   PyObject          * value ) {

    return set_disallow_error( obj, name );
}

/*-----------------------------------------------------------------------------
|  Assigns a value to a specified read-only trait attribute:
+----------------------------------------------------------------------------*/

static int
setattr_readonly ( trait_object      * traito,
                   trait_object      * traitd,
                   has_traits_object * obj,
                   PyObject          * name,
                   PyObject          * value ) {

    PyObject * dict;
    PyObject * result;
    PyObject * nname;
    int rc;

    if ( value == NULL )
        return delete_readonly_error( obj, name );

    if ( traitd->default_value != Undefined )
        return set_readonly_error( obj, name );

        dict = obj->obj_dict;
    if ( dict == NULL )
        return setattr_python( traito, traitd, obj, name, value );

    nname = Py2to3_NormaliseAttrName(name);
    if( nname == NULL ){
        return invalid_attribute_error();
    }

    result = PyDict_GetItem( dict, nname );
    if ( (result == NULL) || (result == Undefined) )
        rc = setattr_python( traito, traitd, obj, nname, value );
    else
        rc = set_readonly_error( obj, nname );

    Py2to3_FinishNormaliseAttrName(name,nname);
    return rc;
}

/*-----------------------------------------------------------------------------
|  Generates exception on attempting to assign to a constant trait:
+----------------------------------------------------------------------------*/

static int
setattr_constant ( trait_object      * traito,
                   trait_object      * traitd,
                   has_traits_object * obj,
                   PyObject          * name,
                   PyObject          * value ) {

    if ( Py2to3_SimpleString_Check( name ) ) {
        PyErr_Format( TraitError,
            "Cannot modify the constant '%.400"
                Py2to3_PYERR_SIMPLE_STRING_FMTCHR "'"
                " attribute of a '%.50s' object.",
            Py2to3_PYERR_PREPARE_SIMPLE_STRING( name ),
            Py_TYPE(obj)->tp_name
        );
        return -1;
    }
    return invalid_attribute_error();
}

/*-----------------------------------------------------------------------------
|  Initializes a CTrait instance:
+----------------------------------------------------------------------------*/

static trait_getattr getattr_handlers[] = {
    getattr_trait,     getattr_python,    getattr_event,  getattr_delegate,
    getattr_event,     getattr_disallow,  getattr_trait,  getattr_constant,
    getattr_generic,
/*  The following entries are used by the __getstate__ method: */
    getattr_property0, getattr_property1, getattr_property2,
    getattr_property3,
/*  End of __getstate__ method entries */
    NULL
};

static trait_setattr setattr_handlers[] = {
    setattr_trait,     setattr_python,    setattr_event,     setattr_delegate,
    setattr_event,     setattr_disallow,  setattr_readonly,  setattr_constant,
    setattr_generic,
/*  The following entries are used by the __getstate__ method: */
    setattr_property0, setattr_property1, setattr_property2, setattr_property3,
/*  End of __setstate__ method entries */
    NULL
};

static int
trait_init ( trait_object * trait, PyObject * args, PyObject * kwds ) {

    int kind;

        if ( !PyArg_ParseTuple( args, "i", &kind ) )
                return -1;

    if ( (kind >= 0) && (kind <= 8) ) {
        trait->getattr = getattr_handlers[ kind ];
        trait->setattr = setattr_handlers[ kind ];
        return 0;
    }

    return bad_trait_error();
}

/*-----------------------------------------------------------------------------
|  Object clearing method:
+----------------------------------------------------------------------------*/

static int
trait_clear ( trait_object * trait ) {

    Py_CLEAR( trait->default_value );
    Py_CLEAR( trait->py_validate );
    Py_CLEAR( trait->py_post_setattr );
    Py_CLEAR( trait->delegate_name );
    Py_CLEAR( trait->delegate_prefix );
    Py_CLEAR( trait->notifiers );
    Py_CLEAR( trait->handler );
    Py_CLEAR( trait->obj_dict );

    return 0;
}

/*-----------------------------------------------------------------------------
|  Deallocates an unused 'CTrait' instance:
+----------------------------------------------------------------------------*/

static void
trait_dealloc ( trait_object * trait ) {

    PyObject_GC_UnTrack(trait);
    Py_TRASHCAN_SAFE_BEGIN(trait);
    trait_clear( trait );
    Py_TYPE(trait)->tp_free( (PyObject *) trait );
    Py_TRASHCAN_SAFE_END(trait);
}

/*-----------------------------------------------------------------------------
|  Garbage collector traversal method:
+----------------------------------------------------------------------------*/

static int
trait_traverse ( trait_object * trait, visitproc visit, void * arg ) {

    Py_VISIT( trait->default_value );
    Py_VISIT( trait->py_validate );
    Py_VISIT( trait->py_post_setattr );
    Py_VISIT( trait->delegate_name );
    Py_VISIT( trait->delegate_prefix );
    Py_VISIT( (PyObject *) trait->notifiers );
    Py_VISIT( trait->handler );
    Py_VISIT( trait->obj_dict );

        return 0;
}

/*-----------------------------------------------------------------------------
|  Casts a 'CTrait' which attempts to validate the argument passed as being a
|  valid value for the trait:
+----------------------------------------------------------------------------*/

static PyObject *
_trait_cast ( trait_object * trait, PyObject * args ) {

    PyObject * obj;
    PyObject * name;
    PyObject * value;
    PyObject * result;
    PyObject * info;

    switch ( PyTuple_GET_SIZE( args ) ) {
        case 1:
            obj   = name = Py_None;
            value = PyTuple_GET_ITEM( args, 0 );
            break;
        case 2:
            name  = Py_None;
            obj   = PyTuple_GET_ITEM( args, 0 );
            value = PyTuple_GET_ITEM( args, 1 );
            break;
        case 3:
            obj   = PyTuple_GET_ITEM( args, 0 );
            name  = PyTuple_GET_ITEM( args, 1 );
            value = PyTuple_GET_ITEM( args, 2 );
            break;
        default:
            PyErr_Format( PyExc_TypeError,
#if PY_VERSION_HEX >= 0x02050000
                "Trait cast takes 1, 2 or 3 arguments (%zd given).",
#else
                "Trait cast takes 1, 2 or 3 arguments (%u given).",
#endif
                PyTuple_GET_SIZE( args ) );
            return NULL;
    }
    if ( trait->validate == NULL ) {
        Py_INCREF( value );
        return value;
    }

        result = trait->validate( trait, (has_traits_object *) obj, name, value );
    if ( result == NULL ) {
        PyErr_Clear();
        info = PyObject_CallMethod( trait->handler, "info", NULL );
        if ( (info != NULL) && Py2to3_SimpleString_Check( info ) )
            PyErr_Format( PyExc_ValueError,
                "Invalid value for trait, the value should be %"
                Py2to3_PYERR_SIMPLE_STRING_FMTCHR ".",
                Py2to3_PYERR_PREPARE_SIMPLE_STRING( info ) );
        else
            PyErr_Format( PyExc_ValueError, "Invalid value for trait." );
        Py_XDECREF( info );
    }

    return result;
}

/*-----------------------------------------------------------------------------
|  Handles the 'getattr' operation on a 'CHasTraits' instance:
+----------------------------------------------------------------------------*/

static PyObject *
trait_getattro ( trait_object * obj, PyObject * name ) {

    PyObject * value = PyObject_GenericGetAttr( (PyObject *) obj, name );
    if ( value != NULL )
        return value;

    PyErr_Clear();

    Py_INCREF( Py_None );
    return Py_None;
}

/*-----------------------------------------------------------------------------
|  Sets the value of the 'default_value' field of a CTrait instance:
+----------------------------------------------------------------------------*/

static PyObject *
_trait_default_value ( trait_object * trait, PyObject * args ) {

    int        value_type;
    PyObject * value;

    if ( PyArg_ParseTuple( args, "" ) ) {
        if ( trait->default_value == NULL )
            return Py_BuildValue( "iO", 0, Py_None );

        return Py_BuildValue( "iO", trait->default_value_type,
                                    trait->default_value );
    }

    if ( !PyArg_ParseTuple( args, "iO", &value_type, &value ) )
        return NULL;

    PyErr_Clear();
    if ( (value_type < 0) || (value_type > 9) ) {
        PyErr_Format( PyExc_ValueError,
                "The default value type must be 0..9, but %d was specified.",
                value_type );

        return NULL;
    }

    Py_INCREF( value );
    Py_XDECREF( trait->default_value );
    trait->default_value_type = value_type;
    trait->default_value = value;

    Py_INCREF( Py_None );
    return Py_None;
}

/*-----------------------------------------------------------------------------
|  Gets the default value of a CTrait instance for a specified object and trait
|  name:
+----------------------------------------------------------------------------*/

static PyObject *
_trait_default_value_for ( trait_object * trait, PyObject * args ) {

    PyObject * object;
    PyObject * name;

    if ( !PyArg_ParseTuple( args, "OO", &object, &name ) )
        return NULL;

    return default_value_for( trait, (has_traits_object *) object, name );
}

/*-----------------------------------------------------------------------------
|  Calls a Python-based trait validator:
+----------------------------------------------------------------------------*/

static PyObject *
validate_trait_python ( trait_object * trait, has_traits_object * obj,
                        PyObject * name, PyObject * value ) {

    PyObject * result;

    PyObject * args = PyTuple_New( 3 );
    if ( args == NULL )
        return NULL;

    Py_INCREF( obj );
    Py_INCREF( name );
    Py_INCREF( value );
    PyTuple_SET_ITEM( args, 0, (PyObject *) obj );
    PyTuple_SET_ITEM( args, 1, name );
    PyTuple_SET_ITEM( args, 2, value );
    result = PyObject_Call( trait->py_validate, args, NULL );
    Py_DECREF( args );

    return result;
}

/*-----------------------------------------------------------------------------
|  Calls the specified validator function:
+----------------------------------------------------------------------------*/

static PyObject *
call_validator ( PyObject * validator, has_traits_object * obj,
                 PyObject * name, PyObject * value ) {

    PyObject * result;

    PyObject * args = PyTuple_New( 3 );
    if ( args == NULL )
        return NULL;

    PyTuple_SET_ITEM( args, 0, (PyObject *) obj );
    PyTuple_SET_ITEM( args, 1, name );
    PyTuple_SET_ITEM( args, 2, value );
    Py_INCREF( obj );
    Py_INCREF( name );
    Py_INCREF( value );
    result = PyObject_Call( validator, args, NULL );
    Py_DECREF( args );

    return result;
}

/*-----------------------------------------------------------------------------
|  Calls the specified type convertor:
+----------------------------------------------------------------------------*/

static PyObject *
type_converter ( PyObject * type, PyObject * value ) {

    PyObject * result;

    PyObject * args = PyTuple_New( 1 );
    if ( args == NULL )
        return NULL;

    PyTuple_SET_ITEM( args, 0, value );
    Py_INCREF( value );
    result = PyObject_Call( type, args, NULL );
    Py_DECREF( args );

    return result;
}

/*-----------------------------------------------------------------------------
|  Verifies a Python value is of a specified type (or None):
+----------------------------------------------------------------------------*/

static PyObject *
validate_trait_type ( trait_object * trait, has_traits_object * obj,
                      PyObject * name, PyObject * value ) {

    PyObject * type_info = trait->py_validate;
    int kind = PyTuple_GET_SIZE( type_info );

    if ( ((kind == 3) && (value == Py_None)) ||
         PyObject_TypeCheck( value,
                 (PyTypeObject *) PyTuple_GET_ITEM( type_info, kind - 1 ) ) ) {

        Py_INCREF( value );
        return value;
    }

    return raise_trait_error( trait, obj, name, value );
}

/*-----------------------------------------------------------------------------
|  Verifies a Python value is an instance of a specified type (or None):
+----------------------------------------------------------------------------*/

static PyObject *
validate_trait_instance ( trait_object * trait, has_traits_object * obj,
                          PyObject * name, PyObject * value ) {

    PyObject * type_info = trait->py_validate;
    int kind = PyTuple_GET_SIZE( type_info );

    if ( ((kind == 3) && (value == Py_None)) ||
        (PyObject_IsInstance( value,
             PyTuple_GET_ITEM( type_info, kind - 1 ) ) > 0) ) {
        Py_INCREF( value );
        return value;
    }

    return raise_trait_error( trait, obj, name, value );
}

/*-----------------------------------------------------------------------------
|  Verifies a Python value is of a the same type as the object being assigned
|  to (or None):
+----------------------------------------------------------------------------*/

static PyObject *
validate_trait_self_type ( trait_object * trait, has_traits_object * obj,
                           PyObject * name, PyObject * value ) {

    if ( ((PyTuple_GET_SIZE( trait->py_validate ) == 2) &&
          (value == Py_None)) ||
          PyObject_TypeCheck( value, Py_TYPE(obj) ) ) {
        Py_INCREF( value );
        return value;
    }

    return raise_trait_error( trait, obj, name, value );
}



/*-----------------------------------------------------------------------------
|  Verifies a Python value is an int within a specified range:
+----------------------------------------------------------------------------*/
#if PY_MAJOR_VERSION < 3
static PyObject *
validate_trait_int ( trait_object * trait, has_traits_object * obj,
                     PyObject * name, PyObject * value ) {

    register PyObject * low;
    register PyObject * high;
    long exclude_mask;
    long int_value;

    PyObject * type_info = trait->py_validate;

    if ( PyInt_Check( value ) ) {
        int_value    = PyInt_AS_LONG( value );
        low          = PyTuple_GET_ITEM( type_info, 1 );
        high         = PyTuple_GET_ITEM( type_info, 2 );
        exclude_mask = PyInt_AS_LONG( PyTuple_GET_ITEM( type_info, 3 ) );
        if ( low != Py_None ) {
            if ( (exclude_mask & 1) != 0 ) {
                if ( int_value <= PyInt_AS_LONG( low ) )
                    goto error;
            } else {
                if ( int_value < PyInt_AS_LONG( low ) )
                    goto error;
            }
        }

        if ( high != Py_None ) {
            if ( (exclude_mask & 2) != 0 ) {
                if ( int_value >= PyInt_AS_LONG( high ) )
                    goto error;
            } else {
                if ( int_value > PyInt_AS_LONG( high ) )
                    goto error;
            }
        }

        Py_INCREF( value );
        return value;
    }
error:
    return raise_trait_error( trait, obj, name, value );
}
#endif  // #if PY_MAJOR_VERSION < 3

/*-----------------------------------------------------------------------------
|  Verifies a Python value is a Python integer (an int or long)
+----------------------------------------------------------------------------*/

static PyObject *
validate_trait_integer ( trait_object * trait, has_traits_object * obj,
                         PyObject * name, PyObject * value ) {
    PyObject *int_value, *result;

    /* Fast paths for the most common cases. */
#if PY_MAJOR_VERSION < 3
    if (PyInt_CheckExact(value)) {
        Py_INCREF(value);
        return value;
    }
    else if (PyLong_CheckExact(value)) {
        long x;
        x = PyLong_AsLong(value);
        if (x == -1 && PyErr_Occurred()) {
            if (PyErr_ExceptionMatches(PyExc_OverflowError)) {
                PyErr_Clear();
                Py_INCREF(value);
                return value;
            }
            return NULL;
        }
        else {
            return PyInt_FromLong(x);
        }
    }
#else
    if (PyLong_CheckExact(value)) {
      Py_INCREF(value);
      return value;
    }
#endif // #if PY_MAJOR_VERSION < 3

    /* General case.  The effect is supposed to be that of
       int(operator.index(value)).  The extra call to 'int' is necessary
       because in Python 2, operator.index (somewhat controversially) does
       *not* always return something of type int or long, but can return
       instances of subclasses of int or long. */
    int_value = PyNumber_Index(value);
    if (int_value == NULL) {
        /* Translate a TypeError to a TraitError, but pass
           on other exceptions. */
        if (PyErr_ExceptionMatches(PyExc_TypeError)) {
            PyErr_Clear();
            goto error;
        }
        return NULL;
    }

#if PY_MAJOR_VERSION < 3
    result = PyNumber_Int(int_value);
#else
    result = PyNumber_Long(int_value);
#endif // #if PY_MAJOR_VERSION < 3
    Py_DECREF(int_value);
    return result;

error:
    return raise_trait_error( trait, obj, name, value );
}

/*-----------------------------------------------------------------------------
|  Verifies a Python value is a float within a specified range:
+----------------------------------------------------------------------------*/

static PyObject *
validate_trait_float ( trait_object * trait, has_traits_object * obj,
                       PyObject * name, PyObject * value ) {

    register PyObject * low;
    register PyObject * high;
    long exclude_mask;
    double float_value;

    PyObject * type_info = trait->py_validate;

    if ( !PyFloat_Check( value ) ) {
        float_value = Py2to3_PyNum_AsDouble( value );
        if( float_value==-1 && PyErr_Occurred() )
            goto error;
        value       = PyFloat_FromDouble( float_value );
        if ( value == NULL )
            goto error;
        Py_INCREF( value );
    } else {
        float_value = PyFloat_AS_DOUBLE( value );
    }

    low          = PyTuple_GET_ITEM( type_info, 1 );
    high         = PyTuple_GET_ITEM( type_info, 2 );
#if PY_MAJOR_VERSION < 3
    exclude_mask = PyInt_AS_LONG( PyTuple_GET_ITEM( type_info, 3 ) );
#else
    exclude_mask = PyLong_AsLong( PyTuple_GET_ITEM( type_info, 3 ) );
    if( exclude_mask==-1 && PyErr_Occurred()){
        goto error;
    }
#endif  // #if PY_MAJOR_VERSION < 3

    if ( low != Py_None ) {
        if ( (exclude_mask & 1) != 0 ) {
            if ( float_value <= PyFloat_AS_DOUBLE( low ) )
                goto error;
        } else {
            if ( float_value < PyFloat_AS_DOUBLE( low ) )
                goto error;
        }
    }

    if ( high != Py_None ) {
        if ( (exclude_mask & 2) != 0 ) {
            if ( float_value >= PyFloat_AS_DOUBLE( high ) )
                goto error;
        } else {
            if ( float_value > PyFloat_AS_DOUBLE( high ) )
                goto error;
        }
    }

    Py_INCREF( value );
    return value;
error:
    return raise_trait_error( trait, obj, name, value );
}

/*-----------------------------------------------------------------------------
|  Verifies a Python value is in a specified enumeration:
+----------------------------------------------------------------------------*/

static PyObject *
validate_trait_enum ( trait_object * trait, has_traits_object * obj,
                      PyObject * name, PyObject * value ) {

    PyObject * type_info = trait->py_validate;
    if ( PySequence_Contains( PyTuple_GET_ITEM( type_info, 1 ), value ) > 0 ) {
        Py_INCREF( value );
        return value;
    }

    return raise_trait_error( trait, obj, name, value );
}

/*-----------------------------------------------------------------------------
|  Verifies a Python value is in a specified map (i.e. dictionary):
+----------------------------------------------------------------------------*/

static PyObject *
validate_trait_map ( trait_object * trait, has_traits_object * obj,
                     PyObject * name, PyObject * value ) {

    PyObject * type_info = trait->py_validate;
    if ( PyDict_GetItem( PyTuple_GET_ITEM( type_info, 1 ), value ) != NULL ) {
        Py_INCREF( value );
        return value;
    }

    return raise_trait_error( trait, obj, name, value );
}

/*-----------------------------------------------------------------------------
|  Verifies a Python value is in a specified prefix map (i.e. dictionary):
+----------------------------------------------------------------------------*/

static PyObject *
validate_trait_prefix_map ( trait_object * trait, has_traits_object * obj,
                            PyObject * name, PyObject * value ) {

    PyObject * type_info    = trait->py_validate;
    PyObject * mapped_value = PyDict_GetItem( PyTuple_GET_ITEM( type_info, 1 ),
                                              value );
    if ( mapped_value != NULL ) {
        Py_INCREF( mapped_value );
        return mapped_value;
    }

    return call_validator( PyTuple_GET_ITEM( trait->py_validate, 2 ),
                           obj, name, value );
}

/*-----------------------------------------------------------------------------
|  Verifies a Python value is a tuple of a specified type and content:
+----------------------------------------------------------------------------*/

static PyObject *
validate_trait_tuple_check ( PyObject * traits, has_traits_object * obj,
                             PyObject * name, PyObject * value ) {

    trait_object * itrait;
    PyObject     * bitem, * aitem, * tuple;
    int i, j, n;

    if ( PyTuple_Check( value ) ) {
        n = PyTuple_GET_SIZE( traits );
        if ( n == PyTuple_GET_SIZE( value ) ) {
            tuple = NULL;
            for ( i = 0; i < n; i++ ) {
                bitem  = PyTuple_GET_ITEM( value, i );
                itrait = (trait_object *) PyTuple_GET_ITEM( traits, i );
                if ( itrait->validate == NULL ) {
                    aitem = bitem;
                    Py_INCREF( aitem );
                } else
                    aitem = itrait->validate( itrait, obj, name, bitem );

                if ( aitem == NULL ) {
                    PyErr_Clear();
                    Py_XDECREF( tuple );
                    return NULL;
                }

                if ( tuple != NULL )
                    PyTuple_SET_ITEM( tuple, i, aitem );
                else if ( aitem != bitem ) {
                    tuple = PyTuple_New( n );
                    if ( tuple == NULL )
                        return NULL;
                    for ( j = 0; j < i; j++ ) {
                        bitem = PyTuple_GET_ITEM( value, j );
                        Py_INCREF( bitem );
                        PyTuple_SET_ITEM( tuple, j, bitem );
                    }
                    PyTuple_SET_ITEM( tuple, i, aitem );
                } else
                    Py_DECREF( aitem );
            }
            if ( tuple != NULL )
                return tuple;

            Py_INCREF( value );
            return value;
        }
    }

    return NULL;
}

static PyObject *
validate_trait_tuple ( trait_object * trait, has_traits_object * obj,
                       PyObject * name, PyObject * value ) {

    PyObject * result = validate_trait_tuple_check(
                            PyTuple_GET_ITEM( trait->py_validate, 1 ),
                            obj, name, value );
    if ( result != NULL )
        return result;

    return raise_trait_error( trait, obj, name, value );
}

/*-----------------------------------------------------------------------------
|  Verifies a Python value is of a specified (possibly coercable) type:
+----------------------------------------------------------------------------*/

static PyObject *
validate_trait_coerce_type ( trait_object * trait, has_traits_object * obj,
                             PyObject * name, PyObject * value ) {

    int i, n;
    PyObject * type2;

    PyObject * type_info = trait->py_validate;
    PyObject * type      = PyTuple_GET_ITEM( type_info, 1 );
    if ( PyObject_TypeCheck( value, (PyTypeObject *) type ) ) {
        Py_INCREF( value );
        return value;
    }

    n = PyTuple_GET_SIZE( type_info );
    for ( i = 2; i < n; i++ ) {
        type2 = PyTuple_GET_ITEM( type_info, i );
        if ( type2 == Py_None )
            break;

        if ( PyObject_TypeCheck( value, (PyTypeObject *) type2 ) ) {
            Py_INCREF( value );
            return value;
        }
    }

    for ( i++; i < n; i++ ) {
        type2 = PyTuple_GET_ITEM( type_info, i );
        if ( PyObject_TypeCheck( value, (PyTypeObject *) type2 ) )
            return type_converter( type, value );
    }

    return raise_trait_error( trait, obj, name, value );
}

/*-----------------------------------------------------------------------------
|  Verifies a Python value is of a specified (possibly castable) type:
+----------------------------------------------------------------------------*/

static PyObject *
validate_trait_cast_type ( trait_object * trait, has_traits_object * obj,
                           PyObject * name, PyObject * value ) {

    PyObject * result;

    PyObject * type_info = trait->py_validate;
    PyObject * type      = PyTuple_GET_ITEM( type_info, 1 );
    if ( PyObject_TypeCheck( value, (PyTypeObject *) type ) ) {
        Py_INCREF( value );
        return value;
    }

    if ( (result = type_converter( type, value )) != NULL )
        return result;

    return raise_trait_error( trait, obj, name, value );
}

/*-----------------------------------------------------------------------------
|  Verifies a Python value satisifies a specified function validator:
+----------------------------------------------------------------------------*/

static PyObject *
validate_trait_function ( trait_object * trait, has_traits_object * obj,
                          PyObject * name, PyObject * value ) {

    PyObject * result;

    result = call_validator( PyTuple_GET_ITEM( trait->py_validate, 1 ),
                             obj, name, value );
    if ( result != NULL )
        return result;

    return raise_trait_error( trait, obj, name, value );
}

/*-----------------------------------------------------------------------------
|  Attempts to 'adapt' an object to a specified interface:
+----------------------------------------------------------------------------*/

static PyObject *
validate_trait_adapt ( trait_object * trait, has_traits_object * obj,
                       PyObject * name, PyObject * value ) {

    PyObject * result;
    PyObject * args;
    PyObject * type;
    PyObject * type_info = trait->py_validate;
    long mode, rc;

    if ( value == Py_None ) {
#if PY_MAJOR_VERSION < 3
        if ( PyInt_AS_LONG( PyTuple_GET_ITEM( type_info, 3 ) ) ) {
#else
        mode = PyLong_AsLong( PyTuple_GET_ITEM( type_info, 3 ) );
        if( mode==-1 && PyErr_Occurred())
            return NULL;
        if ( mode ) {
#endif // #if PY_MAJOR_VERSION < 3
            Py_INCREF( value );
            return value;
        }
        return raise_trait_error( trait, obj, name, value );
    }

    type = PyTuple_GET_ITEM( type_info, 1 );
#if PY_MAJOR_VERSION < 3
    mode = PyInt_AS_LONG( PyTuple_GET_ITEM( type_info, 2 ) );
#else
    mode = PyLong_AsLong( PyTuple_GET_ITEM( type_info, 2 ) );
    if( mode==-1 && PyErr_Occurred())
        return NULL;
#endif // #if PY_MAJOR_VERSION < 3

    if ( mode == 2 ) {
        args = PyTuple_New( 3 );
        if ( args == NULL )
            return NULL;

        PyTuple_SET_ITEM( args, 2, Py_None );
        Py_INCREF( Py_None );
    } else {
        args = PyTuple_New( 2 );
        if ( args == NULL )
            return NULL;
    }

    PyTuple_SET_ITEM( args, 0, value );
    PyTuple_SET_ITEM( args, 1, type );
    Py_INCREF( value );
    Py_INCREF( type );
    result = PyObject_Call( adapt, args, NULL );
    if ( result != NULL ) {
        if ( result != Py_None ) {
            if ( (mode > 0) || (result == value) ) {
                Py_DECREF( args );
                return result;
            }
            Py_DECREF( result );
            goto check_implements;
        }

        Py_DECREF( result );
        result = PyObject_Call( validate_implements, args, NULL );
#if PY_MAJOR_VERSION < 3
        rc     = PyInt_AS_LONG( result );
#else
        rc     = PyLong_AsLong( result );
#endif
        Py_DECREF( args );
        Py_DECREF( result );
#if PY_MAJOR_VERSION >= 3
        if( rc==-1 && PyErr_Occurred()){
            return NULL;
        }
#endif
        if ( rc ) {
            Py_INCREF( value );
            return value;
        }

        result = default_value_for( trait, obj, name );
        if ( result != NULL )
            return result;

        PyErr_Clear();
        return raise_trait_error( trait, obj, name, value );
    }
    PyErr_Clear();
check_implements:
    result = PyObject_Call( validate_implements, args, NULL );
#if PY_MAJOR_VERSION < 3
    rc     = PyInt_AS_LONG( result );
#else
    rc     = PyLong_AsLong( result );
#endif
    Py_DECREF( args );
    Py_DECREF( result );
#if PY_MAJOR_VERSION >= 3
    if( rc==-1 && PyErr_Occurred()){
        return NULL;
    }
#endif
    if ( rc ) {
        Py_INCREF( value );
        return value;
    }

    return raise_trait_error( trait, obj, name, value );
}

/*-----------------------------------------------------------------------------
|  Verifies a Python value satisifies a complex trait definition:
+----------------------------------------------------------------------------*/

static PyObject *
validate_trait_complex ( trait_object * trait, has_traits_object * obj,
                         PyObject * name, PyObject * value ) {

    int    i, j, k, kind;
    long   exclude_mask, mode, rc;
    double float_value;
    PyObject * low, * high, * result, * type_info, * type, * type2, * args;
    PyObject * int_value;

    PyObject * list_type_info = PyTuple_GET_ITEM( trait->py_validate, 1 );
    int n = PyTuple_GET_SIZE( list_type_info );
    for ( i = 0; i < n; i++ ) {

        type_info = PyTuple_GET_ITEM( list_type_info, i );

        switch ( Py2to3_PyNum_AsLong( PyTuple_GET_ITEM( type_info, 0 ) ) ) {

            case 0:  /* Type check: */
                kind = PyTuple_GET_SIZE( type_info );
                if ( ((kind == 3) && (value == Py_None)) ||
                     PyObject_TypeCheck( value, (PyTypeObject *)
                                    PyTuple_GET_ITEM( type_info, kind - 1 ) ) )
                    goto done;
                break;

            case 1:  /* Instance check: */
                kind = PyTuple_GET_SIZE( type_info );
                if ( ((kind == 3) && (value == Py_None)) ||
                    (PyObject_IsInstance( value,
                         PyTuple_GET_ITEM( type_info, kind - 1 ) ) > 0) )
                    goto done;
                break;

            case 2:  /* Self type check: */
                if ( ((PyTuple_GET_SIZE( type_info ) == 2) &&
                      (value == Py_None)) ||
                      PyObject_TypeCheck( value, Py_TYPE(obj) ) )
                    goto done;
                break;

#if PY_MAJOR_VERSION < 3
            case 3:  /* Integer range check: */
                if ( PyInt_Check( value ) ) {
                    long int_value;
                    int_value    = PyInt_AS_LONG( value );
                    low          = PyTuple_GET_ITEM( type_info, 1 );
                    high         = PyTuple_GET_ITEM( type_info, 2 );
                    exclude_mask = PyInt_AS_LONG(
                                       PyTuple_GET_ITEM( type_info, 3 ) );
                    if ( low != Py_None ) {
                        if ( (exclude_mask & 1) != 0 ) {
                            if ( int_value <= PyInt_AS_LONG( low  ) )
                                break;
                        } else {
                            if ( int_value < PyInt_AS_LONG( low  ) )
                                break;
                        }
                    }
                    if ( high != Py_None ) {
                        if ( (exclude_mask & 2) != 0 ) {
                            if ( int_value >= PyInt_AS_LONG( high ) )
                                break;
                        } else {
                            if ( int_value > PyInt_AS_LONG( high ) )
                                break;
                        }
                    }
                    goto done;
                }
                break;
#endif

            case 4:  /* Floating point range check: */
                if ( !PyFloat_Check( value ) ) {
                    float_value = Py2to3_PyNum_AsDouble( value );
                    if( float_value==-1 && PyErr_Occurred() ){
                        PyErr_Clear();
                        break;
                    }

                    value       = PyFloat_FromDouble( float_value );
                    if ( value == NULL ) {
                        PyErr_Clear();
                        break;
                    }
                } else {
                    float_value = PyFloat_AS_DOUBLE( value );
                    Py_INCREF( value );
                }
                low          = PyTuple_GET_ITEM( type_info, 1 );
                high         = PyTuple_GET_ITEM( type_info, 2 );
#if PY_MAJOR_VERSION < 3
                exclude_mask = PyInt_AS_LONG( PyTuple_GET_ITEM( type_info, 3 ) );
#else
                exclude_mask = PyLong_AsLong( PyTuple_GET_ITEM( type_info, 3 ) );
                if( exclude_mask==-1 && PyErr_Occurred()){
                    PyErr_Clear();
                    break;
                }
#endif  // #if PY_MAJOR_VERSION < 3


                if ( low != Py_None ) {
                    if ( (exclude_mask & 1) != 0 ) {
                        if ( float_value <= PyFloat_AS_DOUBLE( low ) )
                            break;
                    } else {
                        if ( float_value < PyFloat_AS_DOUBLE( low ) )
                            break;
                    }
                }
                if ( high != Py_None ) {
                    if ( (exclude_mask & 2) != 0 ) {
                        if ( float_value >= PyFloat_AS_DOUBLE( high ) )
                            break;
                    } else {
                        if ( float_value > PyFloat_AS_DOUBLE( high ) )
                            break;
                    }
                }
                goto done2;

            case 5:  /* Enumerated item check: */
                if ( PySequence_Contains( PyTuple_GET_ITEM( type_info, 1 ),
                                          value ) > 0 )
                    goto done;

                break;
            case 6:  /* Mapped item check: */
                if ( PyDict_GetItem( PyTuple_GET_ITEM( type_info, 1 ),
                                     value ) != NULL )
                    goto done;
                PyErr_Clear();
                break;

            case 8:  /* Perform 'slow' validate check: */
                result = PyObject_CallMethod( PyTuple_GET_ITEM( type_info, 1 ),
                                  "slow_validate", "(OOO)", obj, name, value );
                if ( result != NULL )
                    return result;

                PyErr_Clear();
                break;

            case 9:  /* Tuple item check: */
                result = validate_trait_tuple_check(
                             PyTuple_GET_ITEM( type_info, 1 ),
                             obj, name, value );
                if ( result != NULL )
                    return result;

                PyErr_Clear();
                break;

            case 10:  /* Prefix map item check: */
                result = PyDict_GetItem( PyTuple_GET_ITEM( type_info, 1 ),
                                         value );
                if ( result != NULL ) {
                    Py_INCREF( result );
                    return result;
                }
                result = call_validator( PyTuple_GET_ITEM( type_info, 2 ),
                                         obj, name, value );
                if ( result != NULL )
                    return result;
                PyErr_Clear();
                break;

            case 11:  /* Coercable type check: */
                type = PyTuple_GET_ITEM( type_info, 1 );
                if ( PyObject_TypeCheck( value, (PyTypeObject *) type ) )
                    goto done;

                k = PyTuple_GET_SIZE( type_info );
                for ( j = 2; j < k; j++ ) {
                    type2 = PyTuple_GET_ITEM( type_info, j );
                    if ( type2 == Py_None )
                        break;
                    if ( PyObject_TypeCheck( value, (PyTypeObject *) type2 ) )
                        goto done;
                }

                for ( j++; j < k; j++ ) {
                    type2 = PyTuple_GET_ITEM( type_info, j );
                    if ( PyObject_TypeCheck( value, (PyTypeObject *) type2 ) )
                        return type_converter( type, value );
                }
                break;

            case 12:  /* Castable type check */
                type = PyTuple_GET_ITEM( type_info, 1 );
                if ( PyObject_TypeCheck( value, (PyTypeObject *) type ) )
                    goto done;

                if ( (result = type_converter( type, value )) != NULL )
                    return result;

                PyErr_Clear();
                break;

            case 13:  /* Function validator check: */
                result = call_validator( PyTuple_GET_ITEM( type_info, 1 ),
                                         obj, name, value );
                if ( result != NULL )
                    return result;

                PyErr_Clear();
                break;

            /* case 14: Python-based validator check: */

            /* case 15..18: Property 'setattr' validate checks: */

            case 19:  /* PyProtocols 'adapt' check: */
                if ( value == Py_None ) {
#if PY_MAJOR_VERSION < 3
                    if ( PyInt_AS_LONG( PyTuple_GET_ITEM( type_info, 3 ) ) )
#else
                    mode = PyLong_AsLong( PyTuple_GET_ITEM( type_info, 2 ) );
                    if( mode==-1 && PyErr_Occurred())
                        return NULL;
                    if( mode )
#endif // #if PY_MAJOR_VERSION < 3
                        goto done;
                    break;
                }
                type = PyTuple_GET_ITEM( type_info, 1 );
#if PY_MAJOR_VERSION < 3
                mode = PyInt_AS_LONG( PyTuple_GET_ITEM( type_info, 2 ) );
#else
                mode = PyLong_AsLong( PyTuple_GET_ITEM( type_info, 2 ) );
                if( mode==-1 && PyErr_Occurred())
                    return NULL;
#endif // #if PY_MAJOR_VERSION < 3
                if ( mode == 2 ) {
                    args = PyTuple_New( 3 );
                    if ( args == NULL )
                        return NULL;

                    PyTuple_SET_ITEM( args, 2, Py_None );
                    Py_INCREF( Py_None );
                } else {
                    args = PyTuple_New( 2 );
                    if ( args == NULL )
                        return NULL;
                }

                PyTuple_SET_ITEM( args, 0, value );
                PyTuple_SET_ITEM( args, 1, type );
                Py_INCREF( value );
                Py_INCREF( type );
                result = PyObject_Call( adapt, args, NULL );
                if ( result != NULL ) {
                    if ( result != Py_None ) {
                        if ( (mode == 0) && (result != value) ) {
                            Py_DECREF( result );
                            goto check_implements;
                        }
                        Py_DECREF( args );
                        return result;
                    }

                    Py_DECREF( result );
                    result = PyObject_Call( validate_implements, args, NULL );
#if PY_MAJOR_VERSION < 3
                    rc = PyInt_AS_LONG( result );
#else
                    rc = PyLong_AsLong( result );
                    if( rc==-1 && PyErr_Occurred()){
                        PyErr_Clear();
                        Py_DECREF( args );
                        Py_DECREF( result );
                        break;
                    }
#endif // #if PY_MAJOR_VERSION < 3
                    Py_DECREF( args );
                    Py_DECREF( result );
                    if ( rc )
                        goto done;
                    result = default_value_for( trait, obj, name );
                    if ( result != NULL )
                        return result;

                    PyErr_Clear();
                    break;
                }
                PyErr_Clear();
check_implements:
                result = PyObject_Call( validate_implements, args, NULL );
#if PY_MAJOR_VERSION < 3
                rc = PyInt_AS_LONG( result );
#else
                rc = PyLong_AsLong( result );
                if( rc==-1 && PyErr_Occurred()){
                    PyErr_Clear();
                    Py_DECREF( args );
                    Py_DECREF( result );
                    break;
                }
#endif // #if PY_MAJOR_VERSION < 3
                Py_DECREF( args );
                Py_DECREF( result );
                if ( rc )
                    goto done;
                break;

            case 20:  /* Integer check: */

                /* Fast paths for the most common cases. */
#if PY_MAJOR_VERSION < 3
                if (PyInt_CheckExact(value)) {
                    Py_INCREF(value);
                    return value;
                }
                else if (PyLong_CheckExact(value)) {
                    long x;
                    x = PyLong_AsLong(value);
                    if (x == -1 && PyErr_Occurred()) {
                        if (PyErr_ExceptionMatches(PyExc_OverflowError)) {
                            PyErr_Clear();
                            Py_INCREF(value);
                            return value;
                        }
                        return NULL;
                    }
                    else {
                        return PyInt_FromLong(x);
                    }
                }
#else
                if (PyLong_CheckExact(value)) {
                    Py_INCREF(value);
                    return value;
                }
#endif // #if PY_MAJOR_VERSION < 3
                /* General case. */
                int_value = PyNumber_Index(value);
                if (int_value == NULL) {
                    /* Translate a TypeError to a TraitError, but pass
                       on other exceptions. */
                    if (PyErr_ExceptionMatches(PyExc_TypeError)) {
                        PyErr_Clear();
                        break;
                    }
                    return NULL;
                }
#if PY_MAJOR_VERSION < 3
                result = PyNumber_Int(int_value);
#else
                result = PyNumber_Long(int_value);
#endif // #if PY_MAJOR_VERSION < 3
                Py_DECREF(int_value);
                return result;

            default:  /* Should never happen...indicates an internal error: */
                goto error;
        }
    }
error:
    return raise_trait_error( trait, obj, name, value );
done:
    Py_INCREF( value );
done2:
    return value;
}

/*-----------------------------------------------------------------------------
|  Sets the value of the 'validate' field of a CTrait instance:
+----------------------------------------------------------------------------*/

static trait_validate validate_handlers[] = {
    validate_trait_type,        validate_trait_instance,
#if PY_MAJOR_VERSION < 3
    validate_trait_self_type,   validate_trait_int,
#else
    validate_trait_self_type,   NULL,
#endif // #if PY_MAJOR_VERSION < 3
    validate_trait_float,       validate_trait_enum,
    validate_trait_map,         validate_trait_complex,
    NULL,                       validate_trait_tuple,
    validate_trait_prefix_map,  validate_trait_coerce_type,
    validate_trait_cast_type,   validate_trait_function,
    validate_trait_python,
/*  The following entries are used by the __getstate__ method... */
    setattr_validate0,           setattr_validate1,
    setattr_validate2,           setattr_validate3,
/*  ...End of __getstate__ method entries */
    validate_trait_adapt,        validate_trait_integer,
};

static PyObject *
_trait_set_validate ( trait_object * trait, PyObject * args ) {

    PyObject * validate;
    PyObject * v1, * v2, * v3;
    int        n, kind;

    if ( !PyArg_ParseTuple( args, "O", &validate ) )
        return NULL;

    if ( PyCallable_Check( validate ) ) {
        kind = 14;
        goto done;
    }

    if ( PyTuple_CheckExact( validate ) ) {
        n = PyTuple_GET_SIZE( validate );
        if ( n > 0 ) {

            kind = Py2to3_PyNum_AsLong( PyTuple_GET_ITEM( validate, 0 ) );

            switch ( kind ) {
                case 0:  /* Type check: */
                    if ( (n <= 3) &&
                         PyType_Check( PyTuple_GET_ITEM( validate, n - 1 ) ) &&
                         ((n == 2) ||
                          (PyTuple_GET_ITEM( validate, 1 ) == Py_None)) )
                        goto done;
                    break;

                case 1:  /* Instance check: */
                    if ( (n <= 3) &&
                         ((n == 2) ||
                          (PyTuple_GET_ITEM( validate, 1 ) == Py_None)) )
                        goto done;
                    break;

                case 2:  /* Self type check: */
                    if ( (n == 1) ||
                         ((n == 2) &&
                          (PyTuple_GET_ITEM( validate, 1 ) == Py_None)) )
                        goto done;
                    break;

#if PY_MAJOR_VERSION < 3
                case 3:  /* Integer range check: */
                    if ( n == 4 ) {
                        v1 = PyTuple_GET_ITEM( validate, 1 );
                        v2 = PyTuple_GET_ITEM( validate, 2 );
                        v3 = PyTuple_GET_ITEM( validate, 3 );
                        if ( ((v1 == Py_None) || PyInt_Check( v1 )) &&
                             ((v2 == Py_None) || PyInt_Check( v2 )) &&
                             PyInt_Check( v3 ) )
                            goto done;
                    }
                    break;
#endif // #if PY_MAJOR_VERSION < 3

                case 4:  /* Floating point range check: */
                    if ( n == 4 ) {
                        v1 = PyTuple_GET_ITEM( validate, 1 );
                        v2 = PyTuple_GET_ITEM( validate, 2 );
                        v3 = PyTuple_GET_ITEM( validate, 3 );
                        if ( ((v1 == Py_None) || PyFloat_Check( v1 )) &&
                             ((v2 == Py_None) || PyFloat_Check( v2 )) &&
                             Py2to3_PyNum_Check( v3 ) )
                            goto done;
                    }
                    break;

                case 5:  /* Enumerated item check: */
                    if ( n == 2 ) {
                        v1 = PyTuple_GET_ITEM( validate, 1 );
                        if ( PyTuple_CheckExact( v1 ) )
                            goto done;
                    }
                    break;

                case 6:  /* Mapped item check: */
                    if ( n == 2 ) {
                        v1 = PyTuple_GET_ITEM( validate, 1 );
                        if ( PyDict_Check( v1 ) )
                            goto done;
                    }
                    break;

                case 7:  /* TraitComplex item check: */
                    if ( n == 2 ) {
                        v1 = PyTuple_GET_ITEM( validate, 1 );
                        if ( PyTuple_CheckExact( v1 ) )
                            goto done;
                    }
                    break;

                /* case 8: 'Slow' validate check: */
                case 9:  /* TupleOf item check: */
                    if ( n == 2 ) {
                        v1 = PyTuple_GET_ITEM( validate, 1 );
                        if ( PyTuple_CheckExact( v1 ) )
                            goto done;
                    }
                    break;

                case 10:  /* Prefix map item check: */
                    if ( n == 3 ) {
                        v1 = PyTuple_GET_ITEM( validate, 1 );
                        if ( PyDict_Check( v1 ) )
                            goto done;
                    }
                    break;

                case 11:  /* Coercable type check: */
                    if ( n >= 2 )
                       goto done;
                    break;

                case 12:  /* Castable type check: */
                    if ( n == 2 )
                       goto done;
                    break;

                case 13:  /* Function validator check: */
                    if ( n == 2 ) {
                        v1 = PyTuple_GET_ITEM( validate, 1 );
                        if ( PyCallable_Check( v1 ) )
                            goto done;
                    }
                    break;

                /* case 14: Python-based validator check: */
                /* case 15..18: Property 'setattr' validate checks: */
                case 19:  /* PyProtocols 'adapt' check: */
                    /* Note: We don't check the 'class' argument (item[1])
                       because some old-style code creates classes that are not
                       strictly classes or types (e.g. VTK), and yet they work
                       correctly with the rest of the Instance code */
                    if ( (n == 4) &&
                         Py2to3_PyNum_Check(  PyTuple_GET_ITEM( validate, 2 ) )  &&
                         PyBool_Check( PyTuple_GET_ITEM( validate, 3 ) ) ) {
                        goto done;
                    }
                    break;

                case 20:  /* Integer check: */
                    if ( n == 1 )
                        goto done;
                    break;
            }
        }
    }

    PyErr_SetString( PyExc_ValueError,
                     "The argument must be a tuple or callable." );

    return NULL;

done:
    trait->validate = validate_handlers[ kind ];
    Py_INCREF( validate );
    Py_XDECREF( trait->py_validate );
    trait->py_validate = validate;

    Py_INCREF( Py_None );
    return Py_None;
}

/*-----------------------------------------------------------------------------
|  Gets the value of the 'validate' field of a CTrait instance:
+----------------------------------------------------------------------------*/

static PyObject *
_trait_get_validate ( trait_object * trait ) {

    if ( trait->validate != NULL ) {
        Py_INCREF( trait->py_validate );
        return trait->py_validate;
    }

    Py_INCREF( Py_None );
    return Py_None;
}

/*-----------------------------------------------------------------------------
|  Validates that a particular value can be assigned to an object trait:
+----------------------------------------------------------------------------*/

static PyObject *
_trait_validate ( trait_object * trait, PyObject * args ) {

    PyObject * object, * name, * value;

    if ( !PyArg_ParseTuple( args, "OOO", &object, &name, &value ) )
        return NULL;

    if ( trait->validate == NULL ) {
        Py_INCREF( value );
        return value;
    }

    return trait->validate( trait, (has_traits_object *)object, name, value );
}

/*-----------------------------------------------------------------------------
|  Calls a Python-based trait post_setattr handler:
+----------------------------------------------------------------------------*/

static int
post_setattr_trait_python ( trait_object * trait, has_traits_object * obj,
                            PyObject * name, PyObject * value ) {

    PyObject * result;

    PyObject * args = PyTuple_New( 3 );
    if ( args == NULL )
        return -1;

    Py_INCREF( obj );
    Py_INCREF( name );
    Py_INCREF( value );
    PyTuple_SET_ITEM( args, 0, (PyObject *) obj );
    PyTuple_SET_ITEM( args, 1, name );
    PyTuple_SET_ITEM( args, 2, value );
    result = PyObject_Call( trait->py_post_setattr, args, NULL );
    Py_DECREF( args );

    if ( result == NULL )
        return -1;

    Py_DECREF( result );
    return 0;
}

/*-----------------------------------------------------------------------------
|  Returns the various forms of delegate names:
+----------------------------------------------------------------------------*/

static PyObject *
delegate_attr_name_name ( trait_object      * trait,
                          has_traits_object * obj,
                          PyObject          * name ) {

    Py_INCREF( name );
    return name;
}

static PyObject *
delegate_attr_name_prefix ( trait_object      * trait,
                            has_traits_object * obj,
                            PyObject          * name ) {

    Py_INCREF( trait->delegate_prefix );
    return trait->delegate_prefix;
}

static PyObject *
delegate_attr_name_prefix_name ( trait_object      * trait,
                                 has_traits_object * obj,
                                 PyObject          * name ) {


#if PY_MAJOR_VERSION < 3
    char * p;
    int prefix_len    = PyString_GET_SIZE( trait->delegate_prefix );
    int name_len      = PyString_GET_SIZE( name );
    int total_len     = prefix_len + name_len;
    PyObject * result = PyString_FromStringAndSize( NULL, total_len );

    if ( result == NULL ) {
        Py_INCREF( Py_None );
        return Py_None;
    }

    p = PyString_AS_STRING( result );
    memcpy( p, PyString_AS_STRING( trait->delegate_prefix ), prefix_len );
    memcpy( p + prefix_len, PyString_AS_STRING( name ), name_len );
#else
    PyObject *result = PyUnicode_Concat( trait->delegate_prefix, name );
#endif

    return result;
}

static PyObject *
delegate_attr_name_class_name ( trait_object      * trait,
                                has_traits_object * obj,
                                PyObject          * name ) {

    PyObject * prefix, * result;
#if PY_MAJOR_VERSION < 3
    char * p;
    int prefix_len, name_len, total_len;
#endif

    prefix = PyObject_GetAttr( (PyObject *) Py_TYPE(obj), class_prefix );
// fixme: Should verify that prefix is a string...
    if ( prefix == NULL ) {
            PyErr_Clear();

    Py_INCREF( name );
            return name;
    }

#if PY_MAJOR_VERSION < 3
    prefix_len = PyString_GET_SIZE( prefix );
    name_len   = PyString_GET_SIZE( name );
    total_len  = prefix_len + name_len;
    result     = PyString_FromStringAndSize( NULL, total_len );
    if ( result == NULL ) {
        Py_INCREF( Py_None );
        return Py_None;
    }

    p = PyString_AS_STRING( result );
    memcpy( p, PyString_AS_STRING( prefix ), prefix_len );
    memcpy( p + prefix_len, PyString_AS_STRING( name ), name_len );
#else
    result = PyUnicode_Concat( prefix, name );
#endif
    Py_DECREF( prefix );
    return result;
}

/*-----------------------------------------------------------------------------
|  Sets the value of the 'post_setattr' field of a CTrait instance:
+----------------------------------------------------------------------------*/

static delegate_attr_name_func delegate_attr_name_handlers[] = {
    delegate_attr_name_name,         delegate_attr_name_prefix,
    delegate_attr_name_prefix_name,  delegate_attr_name_class_name,
    NULL
};

static PyObject *
_trait_delegate ( trait_object * trait, PyObject * args ) {

    PyObject * delegate_name;
    PyObject * delegate_prefix;
    int prefix_type;
    int modify_delegate;

#if PY_MAJOR_VERSION < 3
    {
        const char *delegate_name_str;
        const char *delegate_prefix_str;
        if ( !PyArg_ParseTuple( args, "ssii",
                                &delegate_name_str, &delegate_prefix_str,
                                &prefix_type,   &modify_delegate ) )
            return NULL;
        delegate_name = PyString_FromString(delegate_name_str);
        delegate_prefix = PyString_FromString(delegate_prefix_str);
        if(!delegate_name || !delegate_prefix){
            Py_XDECREF(delegate_name);
            Py_XDECREF(delegate_prefix);
            return NULL;
        }
    }
#else
    if ( !PyArg_ParseTuple( args, "UUii",
                            &delegate_name, &delegate_prefix,
                            &prefix_type,   &modify_delegate ) )
        return NULL;
    Py_INCREF( delegate_name );
    Py_INCREF( delegate_prefix );
#endif

    if ( modify_delegate ) {
        trait->flags |= TRAIT_MODIFY_DELEGATE;
    } else {
        trait->flags &= (~TRAIT_MODIFY_DELEGATE);
    }

    trait->delegate_name   = delegate_name;
    trait->delegate_prefix = delegate_prefix;
    if ( (prefix_type < 0) || (prefix_type > 3) )
        prefix_type = 0;

    trait->delegate_attr_name = delegate_attr_name_handlers[ prefix_type ];

    Py_INCREF( Py_None );
    return Py_None;
}

/*-----------------------------------------------------------------------------
|  Sets the value of the 'comparison' mode of a CTrait instance:
+----------------------------------------------------------------------------*/

static PyObject *
_trait_rich_comparison ( trait_object * trait, PyObject * args ) {

    int compare_type;

    if ( !PyArg_ParseTuple( args, "i", &compare_type ) )
        return NULL;

    trait->flags &= (~(TRAIT_NO_VALUE_TEST | TRAIT_OBJECT_IDENTITY));
    if ( compare_type == 0 )
        trait->flags |= TRAIT_OBJECT_IDENTITY;

    Py_INCREF( Py_None );
    return Py_None;
}

/*-----------------------------------------------------------------------------
|  Sets the appropriate value comparison mode flags of a CTrait instance:
+----------------------------------------------------------------------------*/

static PyObject *
_trait_comparison_mode ( trait_object * trait, PyObject * args ) {

    int comparison_mode;

    if ( !PyArg_ParseTuple( args, "i", &comparison_mode ) )
        return NULL;

    trait->flags &= (~(TRAIT_NO_VALUE_TEST | TRAIT_OBJECT_IDENTITY));
    switch ( comparison_mode ) {
        case 0:  trait->flags |= TRAIT_NO_VALUE_TEST;
                 break;
        case 1:  trait->flags |= TRAIT_OBJECT_IDENTITY;
        default: break;
    }

    Py_INCREF( Py_None );
    return Py_None;
}

/*-----------------------------------------------------------------------------
|  Sets the value of the 'value allowed' mode of a CTrait instance:
+----------------------------------------------------------------------------*/

static PyObject *
_trait_value_allowed ( trait_object * trait, PyObject * args ) {

    int value_allowed;

    if ( !PyArg_ParseTuple( args, "i", &value_allowed ) )
        return NULL;

    if ( value_allowed ) {
        trait->flags |= TRAIT_VALUE_ALLOWED;
    } else {
        trait->flags &= (~TRAIT_VALUE_ALLOWED);
    }

    Py_INCREF( Py_None );
    return Py_None;
}

/*-----------------------------------------------------------------------------
|  Sets the value of the 'value trait' mode of a CTrait instance:
+----------------------------------------------------------------------------*/

static PyObject *
_trait_value_property ( trait_object * trait, PyObject * args ) {

    int value_trait;

    if ( !PyArg_ParseTuple( args, "i", &value_trait ) )
        return NULL;

    if ( value_trait ) {
        trait->flags |= TRAIT_VALUE_PROPERTY;
    } else {
        trait->flags &= (~TRAIT_VALUE_PROPERTY);
    }

    Py_INCREF( Py_None );
    return Py_None;
}

/*-----------------------------------------------------------------------------
|  Sets the value of the 'setattr_original_value' flag of a CTrait instance:
+----------------------------------------------------------------------------*/

static PyObject *
_trait_setattr_original_value ( trait_object * trait, PyObject * args ) {

    int original_value;

    if ( !PyArg_ParseTuple( args, "i", &original_value ) )
        return NULL;

    if ( original_value != 0 ) {
        trait->flags |= TRAIT_SETATTR_ORIGINAL_VALUE;
    } else {
        trait->flags &= (~TRAIT_SETATTR_ORIGINAL_VALUE);
    }

    Py_INCREF( trait );
    return (PyObject *) trait;
}

/*-----------------------------------------------------------------------------
|  Sets the value of the 'post_setattr_original_value' flag of a CTrait
|  instance (used in the processing of 'post_settattr' calls):
+----------------------------------------------------------------------------*/

static PyObject *
_trait_post_setattr_original_value ( trait_object * trait, PyObject * args ) {

    int original_value;

    if ( !PyArg_ParseTuple( args, "i", &original_value ) )
        return NULL;

    if ( original_value != 0 ) {
        trait->flags |= TRAIT_POST_SETATTR_ORIGINAL_VALUE;
    } else {
        trait->flags &= (~TRAIT_POST_SETATTR_ORIGINAL_VALUE);
    }

    Py_INCREF( trait );
    return (PyObject *) trait;
}

/*-----------------------------------------------------------------------------
|  Sets the value of the 'is_mapped' flag of a CTrait instance (used in the
|  processing of the default value of a trait with a 'post_settattr' handler):
+----------------------------------------------------------------------------*/

static PyObject *
_trait_is_mapped ( trait_object * trait, PyObject * args ) {

    int is_mapped;

    if ( !PyArg_ParseTuple( args, "i", &is_mapped ) )
        return NULL;

    if ( is_mapped != 0 ) {
        trait->flags |= TRAIT_IS_MAPPED;
    } else {
        trait->flags &= (~TRAIT_IS_MAPPED);
    }

    Py_INCREF( trait );
    return (PyObject *) trait;
}

/*-----------------------------------------------------------------------------
|  Sets the 'property' value fields of a CTrait instance:
+----------------------------------------------------------------------------*/

static trait_setattr setattr_property_handlers[] = {
    setattr_property0, setattr_property1, setattr_property2, setattr_property3,
/*  The following entries are used by the __getstate__ method__: */
    (trait_setattr) post_setattr_trait_python, NULL
};

static PyObject *
_trait_property ( trait_object * trait, PyObject * args ) {

    PyObject * get, * set, * validate, * result, * temp;
    int get_n, set_n, validate_n;

    if ( PyTuple_GET_SIZE( args ) == 0 ) {
        if ( trait->flags & TRAIT_PROPERTY ) {
            result = PyTuple_New( 3 );
            if ( result != NULL ) {
                PyTuple_SET_ITEM( result, 0, temp = trait->delegate_name );
                Py_INCREF( temp );
                PyTuple_SET_ITEM( result, 1, temp = trait->delegate_prefix );
                Py_INCREF( temp );
                PyTuple_SET_ITEM( result, 2, temp = trait->py_validate );
                Py_INCREF( temp );
                return result;
            }
            return NULL;
        } else {
            Py_INCREF( Py_None );
            return Py_None;
        }
    }

    if ( !PyArg_ParseTuple( args, "OiOiOi", &get, &get_n, &set, &set_n,
                                            &validate, &validate_n ) )
        return NULL;
    if ( !PyCallable_Check( get ) || !PyCallable_Check( set )     ||
         ((validate != Py_None) && !PyCallable_Check( validate )) ||
         (get_n < 0)      || (get_n > 3) ||
         (set_n < 0)      || (set_n > 3) ||
         (validate_n < 0) || (validate_n > 3) ) {
        PyErr_SetString( PyExc_ValueError, "Invalid arguments." );
        return NULL;
    }

    trait->flags  |= TRAIT_PROPERTY;
    trait->getattr = getattr_property_handlers[ get_n ];
        if ( validate != Py_None ) {
        trait->setattr      = setattr_validate_property;
        trait->post_setattr = (trait_post_setattr) setattr_property_handlers[
                                                                      set_n ];
        trait->validate     = setattr_validate_handlers[ validate_n ];
        } else
        trait->setattr = setattr_property_handlers[ set_n ];

    trait->delegate_name   = get;
    trait->delegate_prefix = set;
    trait->py_validate     = validate;
    Py_INCREF( get );
    Py_INCREF( set );
    Py_INCREF( validate );
    Py_INCREF( Py_None );
    return Py_None;
}

/*-----------------------------------------------------------------------------
|  Clones one trait into another:
+----------------------------------------------------------------------------*/

static void
trait_clone ( trait_object * trait, trait_object * source ) {

    trait->flags              = source->flags;
    trait->getattr            = source->getattr;
    trait->setattr            = source->setattr;
    trait->post_setattr       = source->post_setattr;
    trait->py_post_setattr    = source->py_post_setattr;
    trait->validate           = source->validate;
    trait->py_validate        = source->py_validate;
    trait->default_value_type = source->default_value_type;
    trait->default_value      = source->default_value;
    trait->delegate_name      = source->delegate_name;
    trait->delegate_prefix    = source->delegate_prefix;
    trait->delegate_attr_name = source->delegate_attr_name;
    trait->handler            = source->handler;
    Py_XINCREF( trait->py_post_setattr );
    Py_XINCREF( trait->py_validate );
    Py_XINCREF( trait->delegate_name );
    Py_XINCREF( trait->default_value );
    Py_XINCREF( trait->delegate_prefix );
    Py_XINCREF( trait->handler );
}

static PyObject *
_trait_clone ( trait_object * trait, PyObject * args ) {

    trait_object * source;

        if ( !PyArg_ParseTuple( args, "O!", ctrait_type, &source ) )
        return NULL;

    trait_clone( trait, source );

    Py_INCREF( Py_None );
    return Py_None;
}

/*-----------------------------------------------------------------------------
|  Returns (and optionally creates) the trait 'notifiers' list:
+----------------------------------------------------------------------------*/

static PyObject *
_trait_notifiers ( trait_object * trait, PyObject * args ) {

    PyObject * result;
    PyObject * list;
    int force_create;

        if ( !PyArg_ParseTuple( args, "i", &force_create ) )
        return NULL;

    result = (PyObject *) trait->notifiers;
    if ( result == NULL ) {
        result = Py_None;
        if ( force_create && ((list = PyList_New( 0 )) != NULL) )
            trait->notifiers = (PyListObject *) (result = list);
    }

    Py_INCREF( result );
    return result;
}

/*-----------------------------------------------------------------------------
|  Converts a function to an index into a function table:
+----------------------------------------------------------------------------*/

static int
func_index ( void * function, void ** function_table ) {

    int i;

    for ( i = 0; function != function_table[i]; i++ );
    return i;
}

/*-----------------------------------------------------------------------------
|  Gets the pickleable state of the trait:
+----------------------------------------------------------------------------*/

static PyObject *
_trait_getstate ( trait_object * trait, PyObject * args ) {

    PyObject * result;

    if ( !PyArg_ParseTuple( args, "" ) )
        return NULL;

    result = PyTuple_New( 15 );
    if ( result == NULL )
        return NULL;

    PyTuple_SET_ITEM( result,  0, Py2to3_PyNum_FromLong( func_index(
                  (void *) trait->getattr, (void **) getattr_handlers ) ) );
    PyTuple_SET_ITEM( result,  1, Py2to3_PyNum_FromLong( func_index(
                  (void *) trait->setattr, (void **) setattr_handlers ) ) );
    PyTuple_SET_ITEM( result,  2, Py2to3_PyNum_FromLong( func_index(
                  (void *) trait->post_setattr,
                  (void **) setattr_property_handlers ) ) );
    PyTuple_SET_ITEM( result,  3, get_callable_value( trait->py_post_setattr ));
    PyTuple_SET_ITEM( result,  4, Py2to3_PyNum_FromLong( func_index(
                  (void *) trait->validate, (void **) validate_handlers ) ) );
    PyTuple_SET_ITEM( result,  5, get_callable_value( trait->py_validate ) );
    PyTuple_SET_ITEM( result,  6, Py2to3_PyNum_FromLong( trait->default_value_type ) );
    PyTuple_SET_ITEM( result,  7, get_value( trait->default_value ) );
    PyTuple_SET_ITEM( result,  8, Py2to3_PyNum_FromLong( trait->flags ) );
    PyTuple_SET_ITEM( result,  9, get_value( trait->delegate_name ) );
    PyTuple_SET_ITEM( result, 10, get_value( trait->delegate_prefix ) );
    PyTuple_SET_ITEM( result, 11, Py2to3_PyNum_FromLong( func_index(
                  (void *) trait->delegate_attr_name,
                  (void **) delegate_attr_name_handlers ) ) );
    PyTuple_SET_ITEM( result, 12, get_value( NULL ) ); /* trait->notifiers */
    PyTuple_SET_ITEM( result, 13, get_value( trait->handler ) );
    PyTuple_SET_ITEM( result, 14, get_value( trait->obj_dict ) );

    return result;
}

/*-----------------------------------------------------------------------------
|  Restores the pickled state of the trait:
+----------------------------------------------------------------------------*/

static PyObject *
_trait_setstate ( trait_object * trait, PyObject * args ) {

    PyObject * ignore, * temp, *temp2;
    int getattr_index, setattr_index, post_setattr_index, validate_index,
        delegate_attr_name_index;

    if ( !PyArg_ParseTuple( args, "(iiiOiOiOiOOiOOO)",
                &getattr_index,             &setattr_index,
                &post_setattr_index,        &trait->py_post_setattr,
                &validate_index,            &trait->py_validate,
                &trait->default_value_type, &trait->default_value,
                &trait->flags,              &trait->delegate_name,
                &trait->delegate_prefix,    &delegate_attr_name_index,
                &ignore,                    &trait->handler,
                &trait->obj_dict ) )
        return NULL;

    trait->getattr      = getattr_handlers[ getattr_index ];
    trait->setattr      = setattr_handlers[ setattr_index ];
    trait->post_setattr = (trait_post_setattr) setattr_property_handlers[
                              post_setattr_index ];
    trait->validate     = validate_handlers[ validate_index ];
    trait->delegate_attr_name = delegate_attr_name_handlers[
                                    delegate_attr_name_index ];

    /* Convert any references to callable methods on the handler back into
       bound methods: */
    temp = trait->py_validate;
    if ( Py2to3_PyNum_Check( temp ) )
        trait->py_validate = PyObject_GetAttrString( trait->handler,
                                                     "validate" );
    else if ( PyTuple_Check( temp ) &&
              (Py2to3_PyNum_AsLong( PyTuple_GET_ITEM( temp, 0 ) ) == 10) ) {
        temp2 = PyObject_GetAttrString( trait->handler, "validate" );
        Py_INCREF( temp2 );
        Py_DECREF( PyTuple_GET_ITEM( temp, 2 ) );
        PyTuple_SET_ITEM( temp, 2, temp2 );
    }

    if ( Py2to3_PyNum_Check( trait->py_post_setattr ) )
        trait->py_post_setattr = PyObject_GetAttrString( trait->handler,
                                                         "post_setattr" );

    Py_INCREF( trait->py_post_setattr );
    Py_INCREF( trait->py_validate );
    Py_INCREF( trait->default_value );
    Py_INCREF( trait->delegate_name );
    Py_INCREF( trait->delegate_prefix );
    Py_INCREF( trait->handler );
    Py_INCREF( trait->obj_dict );

    Py_INCREF( Py_None );
    return Py_None;
}

/*-----------------------------------------------------------------------------
|  Returns the current trait dictionary:
+----------------------------------------------------------------------------*/

static PyObject *
get_trait_dict ( trait_object * trait, void * closure ) {

    PyObject * obj_dict = trait->obj_dict;
    if ( obj_dict == NULL ) {
        trait->obj_dict = obj_dict = PyDict_New();
        if ( obj_dict == NULL )
            return NULL;
    }
    Py_INCREF( obj_dict );
    return obj_dict;
}

/*-----------------------------------------------------------------------------
|  Sets the current trait dictionary:
+----------------------------------------------------------------------------*/

static int
set_trait_dict ( trait_object * trait, PyObject * value, void * closure ) {

    if ( !PyDict_Check( value ) )
        return dictionary_error();
    return set_value( &trait->obj_dict, value );
}

/*-----------------------------------------------------------------------------
|  Returns the current trait handler (if any):
+----------------------------------------------------------------------------*/

static PyObject *
get_trait_handler ( trait_object * trait, void * closure ) {

    return get_value( trait->handler );
}

/*-----------------------------------------------------------------------------
|  Sets the current trait dictionary:
+----------------------------------------------------------------------------*/

static int
set_trait_handler ( trait_object * trait, PyObject * value, void * closure ) {

    return set_value( &trait->handler, value );
}

/*-----------------------------------------------------------------------------
|  Returns the current post_setattr (if any):
+----------------------------------------------------------------------------*/

static PyObject *
get_trait_post_setattr ( trait_object * trait, void * closure ) {

    return get_value( trait->py_post_setattr );
}

/*-----------------------------------------------------------------------------
|  Sets the value of the 'post_setattr' field of a CTrait instance:
+----------------------------------------------------------------------------*/

static int
set_trait_post_setattr ( trait_object * trait, PyObject * value,
                         void * closure ) {

    if ( !PyCallable_Check( value ) ) {
        PyErr_SetString( PyExc_ValueError,
                         "The assigned value must be callable." );
        return -1;
    }
    trait->post_setattr = post_setattr_trait_python;
    return set_value( &trait->py_post_setattr, value );
}

/*-----------------------------------------------------------------------------
|  'CTrait' instance methods:
+----------------------------------------------------------------------------*/

static PyMethodDef trait_methods[] = {
        { "__getstate__", (PyCFunction) _trait_getstate,       METH_VARARGS,
                PyDoc_STR( "__getstate__()" ) },
        { "__setstate__", (PyCFunction) _trait_setstate,       METH_VARARGS,
                PyDoc_STR( "__setstate__(state)" ) },
        { "default_value", (PyCFunction) _trait_default_value, METH_VARARGS,
                PyDoc_STR( "default_value(default_value)" ) },
        { "default_value_for", (PyCFunction) _trait_default_value_for, METH_VARARGS,
                PyDoc_STR( "default_value_for(object,name)" ) },
        { "set_validate",  (PyCFunction) _trait_set_validate,  METH_VARARGS,
                PyDoc_STR( "set_validate(validate_function)" ) },
        { "get_validate",  (PyCFunction) _trait_get_validate,  METH_NOARGS,
                PyDoc_STR( "get_validate()" ) },
        { "validate",      (PyCFunction) _trait_validate,      METH_VARARGS,
                PyDoc_STR( "validate(object,name,value)" ) },
        { "delegate",      (PyCFunction) _trait_delegate,      METH_VARARGS,
                PyDoc_STR( "delegate(delegate_name,prefix,prefix_type,modify_delegate)" ) },
        { "rich_comparison",  (PyCFunction) _trait_rich_comparison,  METH_VARARGS,
                PyDoc_STR( "rich_comparison(rich_comparison_boolean)" ) },
        { "comparison_mode",  (PyCFunction) _trait_comparison_mode,  METH_VARARGS,
                PyDoc_STR( "comparison_mode(comparison_mode_enum)" ) },
        { "value_allowed",  (PyCFunction) _trait_value_allowed,  METH_VARARGS,
                PyDoc_STR( "value_allowed(value_allowed_boolean)" ) },
        { "value_property",  (PyCFunction) _trait_value_property, METH_VARARGS,
                PyDoc_STR( "value_property(value_trait_boolean)" ) },
        { "setattr_original_value",
        (PyCFunction) _trait_setattr_original_value,       METH_VARARGS,
                PyDoc_STR( "setattr_original_value(original_value_boolean)" ) },
        { "post_setattr_original_value",
        (PyCFunction) _trait_post_setattr_original_value,  METH_VARARGS,
                PyDoc_STR( "post_setattr_original_value(original_value_boolean)" ) },
        { "is_mapped", (PyCFunction) _trait_is_mapped,  METH_VARARGS,
                PyDoc_STR( "is_mapped(is_mapped_boolean)" ) },
        { "property",      (PyCFunction) _trait_property,      METH_VARARGS,
                PyDoc_STR( "property([get,set,validate])" ) },
        { "clone",         (PyCFunction) _trait_clone,         METH_VARARGS,
                PyDoc_STR( "clone(trait)" ) },
        { "cast",          (PyCFunction) _trait_cast,          METH_VARARGS,
                PyDoc_STR( "cast(value)" ) },
        { "_notifiers",    (PyCFunction) _trait_notifiers,     METH_VARARGS,
                PyDoc_STR( "_notifiers(force_create)" ) },
        { NULL, NULL },
};

/*-----------------------------------------------------------------------------
|  'CTrait' property definitions:
+----------------------------------------------------------------------------*/

static PyGetSetDef trait_properties[] = {
        { "__dict__",     (getter) get_trait_dict,    (setter) set_trait_dict },
        { "handler",      (getter) get_trait_handler, (setter) set_trait_handler },
        { "post_setattr", (getter) get_trait_post_setattr,
                      (setter) set_trait_post_setattr },
        { 0 }
};

/*-----------------------------------------------------------------------------
|  'CTrait' type definition:
+----------------------------------------------------------------------------*/

static PyTypeObject trait_type = {
    PyVarObject_HEAD_INIT( DEFERRED_ADDRESS( &PyType_Type ), 0 )
    "traits.ctraits.cTrait",
    sizeof( trait_object ),
    0,
    (destructor) trait_dealloc,                    /* tp_dealloc */
    0,                                             /* tp_print */
    0,                                             /* tp_getattr */
    0,                                             /* tp_setattr */
    0,                                             /* tp_compare */
    0,                                             /* tp_repr */
    0,                                             /* tp_as_number */
    0,                                             /* tp_as_sequence */
    0,                                             /* tp_as_mapping */
    0,                                             /* tp_hash */
    0,                                             /* tp_call */
    0,                                             /* tp_str */
    (getattrofunc) trait_getattro,                 /* tp_getattro */
    0,                                             /* tp_setattro */
    0,                                                             /* tp_as_buffer */
    Py_TPFLAGS_DEFAULT | Py_TPFLAGS_BASETYPE | Py_TPFLAGS_HAVE_GC,/* tp_flags */
    0,                                             /* tp_doc */
    (traverseproc) trait_traverse,                 /* tp_traverse */
    (inquiry) trait_clear,                         /* tp_clear */
    0,                                             /* tp_richcompare */
    0,                                             /* tp_weaklistoffset */
    0,                                             /* tp_iter */
    0,                                             /* tp_iternext */
    trait_methods,                                 /* tp_methods */
    0,                                             /* tp_members */
    trait_properties,                              /* tp_getset */
    DEFERRED_ADDRESS( &PyBaseObject_Type ),        /* tp_base */
    0,                                             /* tp_dict */
    0,                                             /* tp_descr_get */
    0,                                             /* tp_descr_set */
    sizeof( trait_object ) - sizeof( PyObject * ), /* tp_dictoffset */
    (initproc) trait_init,                         /* tp_init */
    DEFERRED_ADDRESS( PyType_GenericAlloc ),       /* tp_alloc */
    DEFERRED_ADDRESS( PyType_GenericNew )          /* tp_new */
};

/*-----------------------------------------------------------------------------
|  Sets the global 'Undefined' and 'Uninitialized' values:
+----------------------------------------------------------------------------*/

static PyObject *
_ctraits_undefined ( PyObject * self, PyObject * args ) {

    if ( !PyArg_ParseTuple( args, "OO", &Undefined, &Uninitialized ) )
        return NULL;

    Py_INCREF( Undefined );
    Py_INCREF( Uninitialized );

    Py_INCREF( Py_None );
    return Py_None;
}

/*-----------------------------------------------------------------------------
|  Sets the global 'TraitError' and 'DelegationError' exception types:
+----------------------------------------------------------------------------*/

static PyObject *
_ctraits_exceptions ( PyObject * self, PyObject * args ) {

    if ( !PyArg_ParseTuple( args, "OO", &TraitError, &DelegationError ) )
        return NULL;

    Py_INCREF( TraitError );
    Py_INCREF( DelegationError );

    Py_INCREF( Py_None );
    return Py_None;
}

/*-----------------------------------------------------------------------------
|  Sets the global 'TraitListObject', TraitSetObject and 'TraitDictObject'
|  classes:
+----------------------------------------------------------------------------*/

static PyObject *
_ctraits_list_classes ( PyObject * self, PyObject * args ) {

    if ( !PyArg_ParseTuple( args, "OOO", &TraitListObject, &TraitSetObject,
                                         &TraitDictObject ) )
        return NULL;

    Py_INCREF( TraitListObject );
    Py_INCREF( TraitSetObject );
    Py_INCREF( TraitDictObject );

    Py_INCREF( Py_None );
    return Py_None;
}

/*-----------------------------------------------------------------------------
|  Sets the global 'TraitValue' class:
+----------------------------------------------------------------------------*/

static PyObject *
_ctraits_value_class ( PyObject * self, PyObject * args ) {

    if ( !PyArg_ParseTuple( args, "O", &TraitValue ) )
        return NULL;

    Py_INCREF( TraitValue );

    Py_INCREF( Py_None );
    return Py_None;
}

/*-----------------------------------------------------------------------------
|  Sets the global 'adapt' reference to the PyProtocols 'adapt' function:
+----------------------------------------------------------------------------*/

static PyObject *
_ctraits_adapt ( PyObject * self, PyObject * args ) {

    if ( !PyArg_ParseTuple( args, "O", &adapt ) )
        return NULL;

    Py_INCREF( adapt );

    Py_INCREF( Py_None );
    return Py_None;
}

/*-----------------------------------------------------------------------------
|  Sets the global 'validate_implements' reference to the Python level
|  function:
+----------------------------------------------------------------------------*/

static PyObject *
_ctraits_validate_implements ( PyObject * self, PyObject * args ) {

    if ( !PyArg_ParseTuple( args, "O", &validate_implements ) )
        return NULL;

    Py_INCREF( validate_implements );

    Py_INCREF( Py_None );
    return Py_None;
}

/*-----------------------------------------------------------------------------
|  Sets the global 'ctrait_type' class reference:
+----------------------------------------------------------------------------*/

static PyObject *
_ctraits_ctrait ( PyObject * self, PyObject * args ) {

    if ( !PyArg_ParseTuple( args, "O", &ctrait_type ) )
        return NULL;

    Py_INCREF( ctrait_type );

    Py_INCREF( Py_None );
    return Py_None;
}

/*-----------------------------------------------------------------------------
|  Sets the global 'trait_notification_handler' function, and returns the
|  previous value:
+----------------------------------------------------------------------------*/

static PyObject *
_ctraits_trait_notification_handler ( PyObject * self, PyObject * args ) {

    PyObject * result = _trait_notification_handler;

    if ( !PyArg_ParseTuple( args, "O", &_trait_notification_handler ) ) {
        return NULL;
    }

    if ( _trait_notification_handler == Py_None ) {
        _trait_notification_handler = NULL;
    } else {
        Py_INCREF( _trait_notification_handler );
    }

    if ( result == NULL ) {
        Py_INCREF( Py_None );
        result = Py_None;
    }

    return result;
}

/*-----------------------------------------------------------------------------
|  'CTrait' instance methods:
+----------------------------------------------------------------------------*/

static PyMethodDef ctraits_methods[] = {
        { "_undefined",    (PyCFunction) _ctraits_undefined,    METH_VARARGS,
                PyDoc_STR( "_undefined(Undefined,Uninitialized)" ) },
        { "_exceptions",   (PyCFunction) _ctraits_exceptions,   METH_VARARGS,
                PyDoc_STR( "_exceptions(TraitError,DelegationError)" ) },
        { "_list_classes", (PyCFunction) _ctraits_list_classes, METH_VARARGS,
                PyDoc_STR( "_list_classes(TraitListObject,TraitSetObject,TraitDictObject)" ) },
        { "_value_class", (PyCFunction) _ctraits_value_class,   METH_VARARGS,
                PyDoc_STR( "_value_class(TraitValue)" ) },
        { "_adapt", (PyCFunction) _ctraits_adapt, METH_VARARGS,
                PyDoc_STR( "_adapt(PyProtocols._speedups.adapt)" ) },
        { "_validate_implements", (PyCFunction) _ctraits_validate_implements,
        METH_VARARGS, PyDoc_STR( "_validate_implements(validate_implements)" )},
        { "_ctrait",       (PyCFunction) _ctraits_ctrait,       METH_VARARGS,
                PyDoc_STR( "_ctrait(CTrait_class)" ) },
        { "_trait_notification_handler",
        (PyCFunction) _ctraits_trait_notification_handler,  METH_VARARGS,
        PyDoc_STR( "_trait_notification_handler(handler)" ) },
        { NULL, NULL },
};

/*-----------------------------------------------------------------------------
|  Performs module and type initialization:
+----------------------------------------------------------------------------*/

Py2to3_MOD_INIT(ctraits) {
    PyObject * tmp;

    /* Create the 'ctraits' module: */
    PyObject * module;

    Py2to3_MOD_DEF(
        module,
        "ctraits",
        ctraits__doc__,
        ctraits_methods
    );

    if ( module == NULL )
       return Py2to3_MOD_ERROR_VAL;

    /* Create the 'CHasTraits' type: */
    has_traits_type.tp_base  = &PyBaseObject_Type;
    has_traits_type.tp_alloc = PyType_GenericAlloc;
    if ( PyType_Ready( &has_traits_type ) < 0 )
       return Py2to3_MOD_ERROR_VAL;

    Py_INCREF( &has_traits_type );
    if ( PyModule_AddObject( module, "CHasTraits",
                         (PyObject *) &has_traits_type ) < 0 )
       return Py2to3_MOD_ERROR_VAL;

    /* Create the 'CTrait' type: */
    trait_type.tp_base  = &PyBaseObject_Type;
    trait_type.tp_alloc = PyType_GenericAlloc;
    trait_type.tp_new   = PyType_GenericNew;
    if ( PyType_Ready( &trait_type ) < 0 )
       return Py2to3_MOD_ERROR_VAL;

    Py_INCREF( &trait_type );
    if ( PyModule_AddObject( module, "cTrait",
                         (PyObject *) &trait_type ) < 0 )
       return Py2to3_MOD_ERROR_VAL;

    /* Create the 'HasTraitsMonitor' list: */
    tmp = PyList_New( 0 );
    Py_INCREF( tmp );
    if ( PyModule_AddObject( module, "_HasTraits_monitors",
                             (PyObject*) tmp) < 0 ) {
       return Py2to3_MOD_ERROR_VAL;
    }

    _HasTraits_monitors = tmp;

    /* Predefine a Python string == "__class_traits__": */
    class_traits = Py2to3_SimpleString_FromString( "__class_traits__" );

    /* Predefine a Python string == "__listener_traits__": */
    listener_traits = Py2to3_SimpleString_FromString( "__listener_traits__" );

    /* Predefine a Python string == "editor": */
    editor_property = Py2to3_SimpleString_FromString( "editor" );

    /* Predefine a Python string == "__prefix__": */
    class_prefix = Py2to3_SimpleString_FromString( "__prefix__" );

    /* Predefine a Python string == "trait_added": */
    trait_added = Py2to3_SimpleString_FromString( "trait_added" );

    /* Create an empty tuple: */
    empty_tuple = PyTuple_New( 0 );

    /* Create an empty dict: */
    empty_dict = PyDict_New();

    /* Create the 'is_callable' marker: */
    is_callable = Py2to3_PyNum_FromLong( -1 );

    return Py2to3_MOD_SUCCESS_VAL(module);
}