Comprehensibility patch (typeobject.c)

[davidabrahams]

BPO	536407
Nosy	@gvanrossum, @nascheme
Files	patch: patch contents

^{Note: these values reflect the state of the issue at the time it was migrated and might not reflect the current state.}

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GitHub fields:

assignee = 'https://github.com/gvanrossum'
closed_at = <Date 2002-04-04.17:51:46.000>
created_at = <Date 2002-03-28.18:56:33.000>
labels = ['interpreter-core']
title = 'Comprehensibility patch (typeobject.c)'
updated_at = <Date 2002-04-04.17:51:46.000>
user = 'https://bugs.python.org/davidabrahams'

bugs.python.org fields:

activity = <Date 2002-04-04.17:51:46.000>
actor = 'gvanrossum'
assignee = 'gvanrossum'
closed = True
closed_date = None
closer = None
components = ['Interpreter Core']
creation = <Date 2002-03-28.18:56:33.000>
creator = 'david_abrahams'
dependencies = []
files = ['4093']
hgrepos = []
issue_num = 536407
keywords = ['patch']
message_count = 5.0
messages = ['39401', '39402', '39403', '39404', '39405']
nosy_count = 3.0
nosy_names = ['gvanrossum', 'nascheme', 'david_abrahams']
pr_nums = []
priority = 'normal'
resolution = 'accepted'
stage = None
status = 'closed'
superseder = None
type = None
url = 'https://bugs.python.org/issue536407'
versions = []

[davidabrahams]

--- typeobject.c	Mon Dec 17 12:14:22 2001
+++ typeobject.c.new	Thu Mar 28 13:46:03 2002
@@ -1186,8 +1186,8 @@
 type_getattro(PyTypeObject *type, PyObject *name)
 {
 	PyTypeObject *metatype = type->ob_type;
-	PyObject *descr, *res;
-	descrgetfunc f;
+	PyObject *meta_attribute, *attribute;
+	descrgetfunc meta_get;
 
 	/* Initialize this type (we'll assume the 
metatype is initialized) */
 	if (type->tp_dict == NULL) {
@@ -1195,34 +1195,50 @@
 			return NULL;
 	}
 
-	/* Get a descriptor from the metatype */
-	descr = _PyType_Lookup(metatype, name);
-	f = NULL;
-	if (descr != NULL) {
-		f = descr->ob_type->tp_descr_get;
-		if (f != NULL && PyDescr_IsData
(descr))
-			return f(descr,
-				 (PyObject *)type, 
(PyObject *)metatype);
-	}
+	/* No readable descriptor found yet */
+	meta_get = NULL;
+        
+	/* Look for the attribute in the metatype */
+	meta_attribute = _PyType_Lookup(metatype, 
name);
 
-	/* Look in tp_dict of this type and its bases 
*/
-	res = _PyType_Lookup(type, name);
-	if (res != NULL) {
-		f = res->ob_type->tp_descr_get;
-		if (f != NULL)
-			return f(res, (PyObject *)
NULL, (PyObject *)type);
-		Py_INCREF(res);
-		return res;
+	if (meta_attribute != NULL) {
+		meta_get = meta_attribute->ob_type-
>tp_descr_get;
+                
+		if (meta_get != NULL && PyDescr_IsData
(meta_attribute)) {
+            /* Data descriptors implement 
tp_descr_set to intercept
+             * writes. Assume the attribute is not 
overridden in
+             * type's tp_dict (and bases): call the 
descriptor now.
+             */
+			return meta_get
(meta_attribute,
+                            (PyObject *)type, 
(PyObject *)metatype);
+        }
 	}
 
-	/* Use the descriptor from the metatype */
-	if (f != NULL) {
-		res = f(descr, (PyObject *)type, 
(PyObject *)metatype);
-		return res;
+	/* No data descriptor found on metatype. Look 
in tp_dict of this
+     * type and its bases */
+	attribute = _PyType_Lookup(type, name);
+	if (attribute != NULL) {
+        /* Implement descriptor functionality, if 
any */
+		descrgetfunc local_get = attribute-
>ob_type->tp_descr_get;
+		if (local_get != NULL) {
+            /* NULL 2nd argument indicates the 
descriptor was found on
+             * the target object itself (or a base)  
*/
+			return local_get(attribute, 
(PyObject *)NULL, (PyObject *)type);
+        }
+        
+		Py_INCREF(attribute);
+		return attribute;
 	}
-	if (descr != NULL) {
-		Py_INCREF(descr);
-		return descr;
+
+	/* No attribute found in local __dict__ (or 
bases): use the
+     * descriptor from the metatype, if any */
+	if (meta_get != NULL)
+		return meta_get(meta_attribute, 
(PyObject *)type, (PyObject *)metatype);
+
+    /* If an ordinary attribute was found on the 
metatype, return it now. */
+	if (meta_attribute != NULL) {
+		Py_INCREF(meta_attribute);
+		return meta_attribute;
 	}
 
 	/* Give up */

[davidabrahams]

Logged In: YES
user_id=52572

I have updated the patch so that it is made against the
current sources.

-------

--- typeobject.c	Thu Mar 28 00:33:33 2002
+++ typeobject.c.new	Fri Mar 29 16:20:12 2002
@@ -1237,8 +1237,8 @@
 type_getattro(PyTypeObject *type, PyObject *name)
 {
 	PyTypeObject *metatype = type->ob_type;
-	PyObject *descr, *res;
-	descrgetfunc f;
+	PyObject *meta_attribute, *attribute;
+	descrgetfunc meta_get;
 
 	/* Initialize this type (we'll assume the metatype 
is initialized) */
 	if (type->tp_dict == NULL) {
@@ -1246,40 +1246,56 @@
 			return NULL;
 	}
 
-	/* Get a descriptor from the metatype */
-	descr = _PyType_Lookup(metatype, name);
-	f = NULL;
-	if (descr != NULL) {
-		f = descr->ob_type->tp_descr_get;
-		if (f != NULL && PyDescr_IsData(descr))
-			return f(descr,
-				 (PyObject *)type, 
(PyObject *)metatype);
-	}
+	/* No readable descriptor found yet */
+	meta_get = NULL;
+		
+	/* Look for the attribute in the metatype */
+	meta_attribute = _PyType_Lookup(metatype, name);
 
-	/* Look in tp_dict of this type and its bases */
-	res = _PyType_Lookup(type, name);
-	if (res != NULL) {
-		f = res->ob_type->tp_descr_get;
-		if (f != NULL)
-			return f(res, (PyObject *)NULL, 
(PyObject *)type);
-		Py_INCREF(res);
-		return res;
+	if (meta_attribute != NULL) {
+		meta_get = meta_attribute->ob_type-
>tp_descr_get;
+				
+		if (meta_get != NULL && PyDescr_IsData
(meta_attribute)) {
+			/* Data descriptors implement 
tp_descr_set to intercept
+			 * writes. Assume the attribute is 
not overridden in
+			 * type's tp_dict (and bases): 
call the descriptor now.
+			 */
+			return meta_get(meta_attribute,
+						
	(PyObject *)type, (PyObject *)metatype);
+		}
 	}
 
-	/* Use the descriptor from the metatype */
-	if (f != NULL) {
-		res = f(descr, (PyObject *)type, (PyObject 
*)metatype);
-		return res;
+	/* No data descriptor found on metatype. Look in 
tp_dict of this
+	 * type and its bases */
+	attribute = _PyType_Lookup(type, name);
+	if (attribute != NULL) {
+		/* Implement descriptor functionality, if 
any */
+		descrgetfunc local_get = attribute-
>ob_type->tp_descr_get;
+		if (local_get != NULL) {
+			/* NULL 2nd argument indicates the 
descriptor was found on
+			 * the target object itself (or a 
base)  */
+			return local_get(attribute, 
(PyObject *)NULL, (PyObject *)type);
+		}
+		
+		Py_INCREF(attribute);
+		return attribute;
 	}
-	if (descr != NULL) {
-		Py_INCREF(descr);
-		return descr;
+
+	/* No attribute found in local __dict__ (or 
bases): use the
+	 * descriptor from the metatype, if any */
+	if (meta_get != NULL)
+		return meta_get(meta_attribute, (PyObject 
*)type, (PyObject *)metatype);
+
+	/* If an ordinary attribute was found on the 
metatype, return it now. */
+	if (meta_attribute != NULL) {
+		Py_INCREF(meta_attribute);
+		return meta_attribute;
 	}
 
 	/* Give up */
 	PyErr_Format(PyExc_AttributeError,
-		     "type object '%.50s' has no 
attribute '%.400s'",
-		     type->tp_name, PyString_AS_STRING
(name));
+			 "type object '%.50s' has no 
attribute '%.400s'",
+			 type->tp_name, PyString_AS_STRING
(name));
 	return NULL;
 }

[nascheme]

Logged In: YES
user_id=35752

Don't paste the patch in the comment box.

[davidabrahams]

Logged In: YES
user_id=52572

Thanks, Neil, I think I got the picture already (see
Python-Dev).

[gvanrossum]

Logged In: YES
user_id=6380

Thanks, applied (after folding some long lines).

Next time, please don't call the patch "patch". Call it
something like "typeobject.patch".