/
properties.pyx
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/
properties.pyx
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'''
Properties
==========
The *Properties* classes are used when you create a
:class:`~kivy.event.EventDispatcher`.
.. warning::
Kivy's Properties are **not to be confused** with Python's
properties (i.e. the ``@property`` decorator and the <property> type).
Kivy's property classes support:
Value Checking / Validation
When you assign a new value to a property, the value is checked to
pass constraints implemented in the class such as validation. For
example, validation for :class:`OptionProperty` will make sure that
the value is in a predefined list of possibilities. Validation for
:class:`NumericProperty` will check that your value is a numeric type.
This prevents many errors early on.
Observer Pattern
You can specify what should happen when a property's value changes.
You can bind your own function as a callback to changes of a
:class:`Property`. If, for example, you want a piece of code to be
called when a widget's :class:`~kivy.uix.widget.Widget.pos` property
changes, you can :class:`~kivy.event.EventDispatcher.bind` a function
to it.
Better Memory Management
The same instance of a property is shared across multiple widget
instances.
Comparison Python / Kivy
------------------------
Basic example
~~~~~~~~~~~~~
Let's compare Python and Kivy properties by creating a Python class with 'a'
as a float::
class MyClass(object):
def __init__(self, a=1.0):
super(MyClass, self).__init__()
self.a = a
With Kivy, you can do::
class MyClass(EventDispatcher):
a = NumericProperty(1.0)
Value checking
~~~~~~~~~~~~~~
If you wanted to add a check such a minimum / maximum value allowed for a
property, here is a possible implementation in Python::
class MyClass(object):
def __init__(self, a=1):
super(MyClass, self).__init__()
self._a = 0
self.a_min = 0
self.a_max = 100
self.a = a
def _get_a(self):
return self._a
def _set_a(self, value):
if value < self.a_min or value > self.a_max:
raise ValueError('a out of bounds')
self._a = a
a = property(_get_a, _set_a)
The disadvantage is you have to do that work yourself. And it becomes
laborious and complex if you have many properties.
With Kivy, you can simplify like this::
class MyClass(EventDispatcher):
a = BoundedNumericProperty(1, min=0, max=100)
That's all!
Error Handling
~~~~~~~~~~~~~~
If setting a value would otherwise raise a ValueError, you have two options to
handle the error gracefully within the property. An errorvalue is a substitute
for the invalid value. An errorhandler is a callable (single argument function
or lambda) which can return a valid substitute.
errorhandler parameter::
# simply returns 0 if the value exceeds the bounds
bnp = BoundedNumericProperty(0, min=-500, max=500, errorvalue=0)
errorvalue parameter::
# returns a the boundary value when exceeded
bnp = BoundedNumericProperty(0, min=-500, max=500,
errorhandler=lambda x: 500 if x > 500 else -500)
Conclusion
~~~~~~~~~~
Kivy properties are easier to use than the standard ones. See the next chapter
for examples of how to use them :)
Observe Properties changes
--------------------------
As we said in the beginning, Kivy's Properties implement the `Observer pattern
<http://en.wikipedia.org/wiki/Observer_pattern>`_. That means you can
:meth:`~kivy.event.EventDispatcher.bind` to a property and have your own
function called when the value changes.
Multiple ways are available to observe the changes.
Observe using bind()
~~~~~~~~~~~~~~~~~~~~
You can observe a property change by using the bind() method, outside the
class::
class MyClass(EventDispatcher):
a = NumericProperty(1)
def callback(instance, value):
print 'My callback is call from', instance,
print 'and the a value changed to', value
ins = MyClass()
ins.bind(a=callback)
# At this point, any change to the a property will call your callback.
ins.a = 5 # callback called
ins.a = 5 # callback not called, because the value didnt change
ins.a = -1 # callback called
Observe using 'on_<propname>'
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
If you created the class yourself, you can use the 'on_<propname>' callback::
class MyClass(EventDispatcher):
a = NumericProperty(1)
def on_a(self, instance, value):
print 'My property a changed to', value
.. warning::
Be careful with 'on_<propname>'. If you are creating such a callback on a
property you are inherit, you must not forget to call the subclass
function too.
'''
__all__ = ('Property',
'NumericProperty', 'StringProperty', 'ListProperty',
'ObjectProperty', 'BooleanProperty', 'BoundedNumericProperty',
'OptionProperty', 'ReferenceListProperty', 'AliasProperty',
'DictProperty')
from weakref import ref
cdef float g_dpi = -1
cdef float g_density = -1
cdef float g_fontscale = -1
cpdef float dpi2px(value, ext):
# 1in = 2.54cm = 25.4mm = 72pt = 12pc
global g_dpi, g_density, g_fontscale
if g_dpi == -1:
from kivy.metrics import metrics
g_dpi = metrics.dpi
g_density = metrics.density
g_fontscale = metrics.fontscale
cdef float rv = float(value)
if ext == 'in':
return rv * g_dpi
elif ext == 'px':
return rv
elif ext == 'dp':
return rv * g_density
elif ext == 'sp':
return rv * g_density * g_fontscale
elif ext == 'pt':
return rv * g_dpi / 72.
elif ext == 'cm':
return rv * g_dpi / 2.54
elif ext == 'mm':
return rv * g_dpi / 25.4
cdef class Property:
'''Base class for building more complex properties.
This class handles all the basic setters and getters, None type handling,
the observer list and storage initialisation. This class should not be
directly instantiated.
By default, a :class:`Property` always takes a default value::
class MyObject(Widget):
hello = Property('Hello world')
The default value must be a value that agrees with the Property type. For
example, you can't set a list to a :class:`StringProperty`, because the
StringProperty will check the default value.
None is a special case: you can set the default value of a Property to
None, but you can't set None to a property afterward. If you really want
to do that, you must declare the Property with `allownone=True`::
class MyObject(Widget):
hello = ObjectProperty(None, allownone=True)
# then later
a = MyObject()
a.hello = 'bleh' # working
a.hello = None # working too, because allownone is True.
:Parameters:
`errorhandler`: callable
If set, must take a single argument and return a valid substitute
value
`errorvalue`: object
If set, will replace an invalid property value (overrides
errorhandler)
.. versionchanged:: 1.4.2
Parameters errorhandler and errorvalue added
'''
def __cinit__(self):
self._name = ''
self.allownone = 0
self.defaultvalue = None
self.errorvalue = None
self.errorhandler = None
self.errorvalue_set = 0
def __init__(self, defaultvalue, **kw):
self.defaultvalue = defaultvalue
self.allownone = <int>kw.get('allownone', 0)
self.errorvalue = kw.get('errorvalue', None)
self.errorhandler = kw.get('errorhandler', None)
if 'errorvalue' in kw:
self.errorvalue_set = 1
if 'errorhandler' in kw and not callable(self.errorhandler):
raise ValueError('errorhandler %s not callable' % self.errorhandler)
property name:
def __get__(self):
return self._name
cdef init_storage(self, EventDispatcher obj, dict storage):
storage['value'] = self.convert(obj, self.defaultvalue)
storage['observers'] = []
cpdef link(self, EventDispatcher obj, str name):
'''Link the instance with its real name.
.. warning::
Internal usage only.
When a widget is defined and uses a :class:`Property` class, the
creation of the property object happens, but the instance doesn't know
anything about its name in the widget class::
class MyWidget(Widget):
uid = NumericProperty(0)
In this example, the uid will be a NumericProperty() instance, but the
property instance doesn't know its name. That's why :func:`link` is
used in Widget.__new__. The link function is also used to create the
storage space of the property for this specific widget instance.
'''
d = dict()
self._name = name
obj.__storage[name] = d
self.init_storage(obj, d)
cpdef link_deps(self, EventDispatcher obj, str name):
pass
cpdef bind(self, EventDispatcher obj, observer):
'''Add a new observer to be called only when the value is changed.
'''
cdef list observers = obj.__storage[self._name]['observers']
if not observer in observers:
observers.append(observer)
cpdef unbind(self, EventDispatcher obj, observer):
'''Remove the observer from our widget observer list.
'''
cdef list observers = obj.__storage[self._name]['observers']
for item in observers[:]:
if item == observer:
observers.remove(item)
def __set__(self, EventDispatcher obj, val):
self.set(obj, val)
def __get__(self, EventDispatcher obj, objtype):
if obj is None:
return self
return self.get(obj)
cdef compare_value(self, a, b):
return a == b
cpdef set(self, EventDispatcher obj, value):
'''Set a new value for the property.
'''
value = self.convert(obj, value)
d = obj.__storage[self._name]
realvalue = d['value']
if self.compare_value(realvalue, value):
return False
try:
self.check(obj, value)
except ValueError as e:
if self.errorvalue_set == 1:
value = self.errorvalue
self.check(obj, value)
elif self.errorhandler is not None:
value = self.errorhandler(value)
self.check(obj, value)
else:
raise e
d['value'] = value
self.dispatch(obj)
return True
cpdef get(self, EventDispatcher obj):
'''Return the value of the property.
'''
return obj.__storage[self._name]['value']
#
# Private part
#
cdef check(self, EventDispatcher obj, x):
'''Check if the value is correct or not, depending on the settings of
the property class.
:Returns:
bool, True if the value correctly validates.
'''
if x is None:
if not self.allownone:
raise ValueError('None is not allowed for %s.%s' % (
obj.__class__.__name__,
self.name))
else:
return True
cdef convert(self, EventDispatcher obj, x):
'''Convert the initial value to a correctly validating value.
Can be used for multiple types of arguments, simplifying to only one.
'''
return x
cpdef dispatch(self, EventDispatcher obj):
'''Dispatch the value change to all observers.
.. versionchanged:: 1.1.0
The method is now accessible from Python.
This can be used to force the dispatch of the property, even if the
value didn't change::
button = Button()
# get the Property class instance
prop = button.property('text')
# dispatch this property on the button instance
prop.dispatch(button)
'''
cdef dict storage = obj.__storage[self._name]
cdef list observers = storage['observers']
if len(observers):
value = storage['value']
for observer in observers:
observer(obj, value)
cdef class NumericProperty(Property):
'''Property that represents a numeric value.
The NumericProperty accepts only int or float.
>>> wid = Widget()
>>> wid.x = 42
>>> print wid.x
42
>>> wid.x = "plop"
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
File "properties.pyx", line 93, in kivy.properties.Property.__set__
File "properties.pyx", line 111, in kivy.properties.Property.set
File "properties.pyx", line 159, in kivy.properties.NumericProperty.check
ValueError: NumericProperty accept only int/float
.. versionchanged:: 1.4.1
NumericProperty can now accept custom text and tuple value to indicate a
type, like "in", "pt", "px", "cm", "mm", in the format: '10pt' or (10,
'pt').
'''
def __init__(self, defaultvalue=0, **kw):
super(NumericProperty, self).__init__(defaultvalue, **kw)
cdef init_storage(self, EventDispatcher obj, dict storage):
storage['format'] = 'px'
Property.init_storage(self, obj, storage)
cdef check(self, EventDispatcher obj, value):
if Property.check(self, obj, value):
return True
if type(value) not in (int, float):
raise ValueError('%s.%s accept only int/float (got %r)' % (
obj.__class__.__name__,
self.name, value))
cdef convert(self, EventDispatcher obj, x):
if x is None:
return x
tp = type(x)
if tp is int or tp is float:
return x
if tp is tuple or tp is list:
if len(x) != 2:
raise ValueError('%s.%s must have 2 components (got %r)' % (
obj.__class__.__name__,
self.name, x))
return self.parse_list(obj, x[0], <str>x[1])
elif tp is str:
return self.parse_str(obj, x)
else:
raise ValueError('%s.%s have an invalid format (got %r)' % (
obj.__class__.__name__,
self.name, x))
cdef float parse_str(self, EventDispatcher obj, value):
return self.parse_list(obj, value[:-2], <str>value[-2:])
cdef float parse_list(self, EventDispatcher obj, value, str ext):
obj.__storage[self.name]['format'] = ext
return dpi2px(value, ext)
def get_format(self, EventDispatcher obj):
'''
Return the format used for Numeric calculation. Default is px (mean
the value have not been changed at all). Otherwise, it can be one of
'in', 'pt', 'cm', 'mm'.
'''
return obj.__storage[self.name]['format']
cdef class StringProperty(Property):
'''Property that represents a string value.
Only a string or unicode is accepted.
'''
def __init__(self, defaultvalue='', **kw):
super(StringProperty, self).__init__(defaultvalue, **kw)
cdef check(self, EventDispatcher obj, value):
if Property.check(self, obj, value):
return True
if not isinstance(value, basestring):
raise ValueError('%s.%s accept only str/unicode' % (
obj.__class__.__name__,
self.name))
cdef inline void observable_list_dispatch(object self):
cdef Property prop = self.prop
obj = self.obj()
if obj is not None:
prop.dispatch(obj)
class ObservableList(list):
# Internal class to observe changes inside a native python list.
def __init__(self, *largs):
self.prop = largs[0]
self.obj = ref(largs[1])
super(ObservableList, self).__init__(*largs[2:])
def __setitem__(self, key, value):
list.__setitem__(self, key, value)
observable_list_dispatch(self)
def __delitem__(self, key):
list.__delitem__(self, key)
observable_list_dispatch(self)
def __setslice__(self, *largs):
list.__setslice__(self, *largs)
observable_list_dispatch(self)
def __delslice__(self, *largs):
list.__delslice__(self, *largs)
observable_list_dispatch(self)
def __iadd__(self, *largs):
list.__iadd__(self, *largs)
observable_list_dispatch(self)
def __imul__(self, *largs):
list.__imul__(self, *largs)
observable_list_dispatch(self)
def append(self, *largs):
list.append(self, *largs)
observable_list_dispatch(self)
def remove(self, *largs):
list.remove(self, *largs)
observable_list_dispatch(self)
def insert(self, *largs):
list.insert(self, *largs)
observable_list_dispatch(self)
def pop(self, *largs):
cdef object result = list.pop(self, *largs)
observable_list_dispatch(self)
return result
def extend(self, *largs):
list.extend(self, *largs)
observable_list_dispatch(self)
def sort(self, *largs):
list.sort(self, *largs)
observable_list_dispatch(self)
def reverse(self, *largs):
list.reverse(self, *largs)
observable_list_dispatch(self)
cdef class ListProperty(Property):
'''Property that represents a list.
Only lists are allowed. Tuple or any other classes are forbidden.
'''
def __init__(self, defaultvalue=None, **kw):
defaultvalue = defaultvalue or []
super(ListProperty, self).__init__(defaultvalue, **kw)
cpdef link(self, EventDispatcher obj, str name):
Property.link(self, obj, name)
storage = obj.__storage[self._name]
storage['value'] = ObservableList(self, obj, storage['value'])
cdef check(self, EventDispatcher obj, value):
if Property.check(self, obj, value):
return True
if type(value) is not ObservableList:
raise ValueError('%s.%s accept only ObservableList' % (
obj.__class__.__name__,
self.name))
cpdef set(self, EventDispatcher obj, value):
value = ObservableList(self, obj, value)
Property.set(self, obj, value)
cdef inline void observable_dict_dispatch(object self):
cdef Property prop = self.prop
prop.dispatch(self.obj)
class ObservableDict(dict):
# Internal class to observe changes inside a native python dict.
def __init__(self, *largs):
self.prop = largs[0]
self.obj = largs[1]
super(ObservableDict, self).__init__(*largs[2:])
def __getattr__(self, attr):
try:
return self.__getitem__(attr)
except KeyError:
try:
return super(ObservableDict, self).__getattr__(attr)
except AttributeError:
raise KeyError(attr)
def __setattr__(self, attr, value):
if attr in ('prop', 'obj'):
super(ObservableDict, self).__setattr__(attr, value)
return
self.__setitem__(attr, value)
def __setitem__(self, key, value):
if value is None:
# remove attribute if value is None
# is this really needed?
self.__delitem__(key)
else:
dict.__setitem__(self, key, value)
observable_dict_dispatch(self)
def __delitem__(self, key):
dict.__delitem__(self, key)
observable_dict_dispatch(self)
def clear(self, *largs):
dict.append(self, *largs)
observable_dict_dispatch(self)
def remove(self, *largs):
dict.remove(self, *largs)
observable_dict_dispatch(self)
def pop(self, *largs):
cdef object result = dict.pop(self, *largs)
observable_dict_dispatch(self)
return result
def popitem(self, *largs):
cdef object result = dict.popitem(self, *largs)
observable_dict_dispatch(self)
return result
def setdefault(self, *largs):
dict.setdefault(self, *largs)
observable_dict_dispatch(self)
def update(self, *largs):
dict.update(self, *largs)
observable_dict_dispatch(self)
cdef class DictProperty(Property):
'''Property that represents a dict.
Only dict are allowed. Any other classes are forbidden.
'''
def __init__(self, defaultvalue=None, **kw):
defaultvalue = defaultvalue or {}
super(DictProperty, self).__init__(defaultvalue, **kw)
cpdef link(self, EventDispatcher obj, str name):
Property.link(self, obj, name)
storage = obj.__storage[self._name]
storage['value'] = ObservableDict(self, obj, storage['value'])
cdef check(self, EventDispatcher obj, value):
if Property.check(self, obj, value):
return True
if type(value) is not ObservableDict:
raise ValueError('%s.%s accept only ObservableDict' % (
obj.__class__.__name__,
self.name))
cpdef set(self, EventDispatcher obj, value):
value = ObservableDict(self, obj, value)
Property.set(self, obj, value)
cdef class ObjectProperty(Property):
'''Property that represents a Python object.
.. warning::
To mark the property as changed, you must reassign a new python object.
'''
def __init__(self, defaultvalue=None, **kw):
super(ObjectProperty, self).__init__(defaultvalue, **kw)
cdef check(self, EventDispatcher obj, value):
if Property.check(self, obj, value):
return True
if not isinstance(value, object):
raise ValueError('%s.%s accept only Python object' % (
obj.__class__.__name__,
self.name))
cdef class BooleanProperty(Property):
'''Property that represents only a boolean value.
'''
def __init__(self, defaultvalue=True, **kw):
super(BooleanProperty, self).__init__(defaultvalue, **kw)
cdef check(self, EventDispatcher obj, value):
if Property.check(self, obj, value):
return True
if not isinstance(value, object):
raise ValueError('%s.%s accept only bool' % (
obj.__class__.__name__,
self.name))
cdef class BoundedNumericProperty(Property):
'''Property that represents a numeric value within a minimum bound and/or
maximum bound -- within a numeric range.
:Parameters:
`min`: numeric
If set, minimum bound will be used, with the value of min
`max`: numeric
If set, maximum bound will be used, with the value of max
'''
def __cinit__(self):
self.use_min = 0
self.use_max = 0
self.min = 0
self.max = 0
self.f_min = 0.0
self.f_max = 0.0
def __init__(self, *largs, **kw):
value = kw.get('min', None)
if value is None:
self.use_min = 0
elif type(value) is float:
self.use_min = 2
self.f_min = value
else:
self.use_min = 1
self.min = value
value = kw.get('max', None)
if value is None:
self.use_max = 0
elif type(value) is float:
self.use_max = 2
self.f_max = value
else:
self.use_max = 1
self.max = value
Property.__init__(self, *largs, **kw)
cdef init_storage(self, EventDispatcher obj, dict storage):
Property.init_storage(self, obj, storage)
storage['min'] = self.min
storage['max'] = self.max
storage['f_min'] = self.f_min
storage['f_max'] = self.f_max
storage['use_min'] = self.use_min
storage['use_max'] = self.use_max
def set_min(self, EventDispatcher obj, value):
'''Change the minimum value acceptable for the BoundedNumericProperty,
only for the `obj` instance. Set to None if you want to disable it::
class MyWidget(Widget):
number = BoundedNumericProperty(0, min=-5, max=5)
widget = MyWidget()
# change the minmium to -10
widget.property('number').set_min(widget, -10)
# or disable the minimum check
widget.property('number').set_min(widget, None)
.. warning::
Changing the bounds doesn't revalidate the current value.
.. versionadded:: 1.1.0
'''
cdef dict s = obj.__storage[self._name]
if value is None:
s['use_min'] = 0
elif type(value) is float:
s['f_min'] = value
s['use_min'] = 2
else:
s['min'] = value
s['use_min'] = 1
def get_min(self, EventDispatcher obj):
'''Return the minimum value acceptable for the BoundedNumericProperty
in `obj`. Return None if no minimum value is set::
class MyWidget(Widget):
number = BoundedNumericProperty(0, min=-5, max=5)
widget = MyWidget()
print widget.property('number').get_min(widget)
# will output -5
.. versionadded:: 1.1.0
'''
cdef dict s = obj.__storage[self._name]
if s['use_min'] == 1:
return s['min']
elif s['use_min'] == 2:
return s['f_min']
def set_max(self, EventDispatcher obj, value):
'''Change the maximum value acceptable for the BoundedNumericProperty,
only for the `obj` instance. Set to None if you want to disable it.
Check :data:`set_min` for a usage example.
.. warning::
Changing the bounds doesn't revalidate the current value.
.. versionadded:: 1.1.0
'''
cdef dict s = obj.__storage[self._name]
if value is None:
s['use_max'] = 0
elif type(value) is float:
s['f_max'] = value
s['use_max'] = 2
else:
s['max'] = value
s['use_max'] = 1
def get_max(self, EventDispatcher obj):
'''Return the maximum value acceptable for the BoundedNumericProperty
in `obj`. Return None if no maximum value is set. Check
:data:`get_min` for a usage example.
.. versionadded:: 1.1.0
'''
cdef dict s = obj.__storage[self._name]
if s['use_max'] == 1:
return s['max']
if s['use_max'] == 2:
return s['f_max']
cdef check(self, EventDispatcher obj, value):
if Property.check(self, obj, value):
return True
s = obj.__storage[self._name]
if s['use_min'] == 1:
_min = s['min']
if value < _min:
raise ValueError('%s.%s is below the minimum bound (%d)' % (
obj.__class__.__name__,
self.name, _min))
elif s['use_min'] == 2:
_min = s['f_min']
if value < _min:
raise ValueError('%s.%s is below the minimum bound (%d)' % (
obj.__class__.__name__,
self.name, _min))
if s['use_max'] == 1:
_max = s['max']
if value > _max:
raise ValueError('%s.%s is above the maximum bound (%d)' % (
obj.__class__.__name__,
self.name, _max))
elif s['use_max'] == 2:
_max = s['f_max']
if value > _max:
raise ValueError('%s.%s is above the maximum bound (%d)' % (
obj.__class__.__name__,
self.name, _max))
return True
property bounds:
'''Return min/max of the value.
.. versionadded:: 1.0.9
'''
def __get__(self):
if self.use_min == 1:
_min = self.min
elif self.use_min == 2:
_min = self.f_min
else:
_min = None
if self.use_max == 1:
_max = self.max
elif self.use_max == 2:
_max = self.f_max
else:
_max = None
return _min, _max
cdef class OptionProperty(Property):
'''Property that represents a string from a predefined list of valid
options.
If the string set in the property is not in the list of valid options
(passed at property creation time), a ValueError exception will be raised.
:Parameters:
`options`: list (not tuple.)
List of valid options
'''
def __cinit__(self):
self.options = []
def __init__(self, *largs, **kw):
self.options = <list>(kw.get('options', []))
super(OptionProperty, self).__init__(*largs, **kw)
cdef init_storage(self, EventDispatcher obj, dict storage):
Property.init_storage(self, obj, storage)
storage['options'] = self.options[:]
cdef check(self, EventDispatcher obj, value):
if Property.check(self, obj, value):
return True
valid_options = obj.__storage[self._name]['options']
if value not in valid_options:
raise ValueError('%s.%s is set to an invalid option %r. '
'Must be one of: %s' % (
obj.__class__.__name__,
self.name,
value, valid_options))
property options:
'''Return the options available.
.. versionadded:: 1.0.9
'''
def __get__(self):
return self.options
cdef class ReferenceListProperty(Property):
'''Property that allows the creaton of a tuple of other properties.
For example, if `x` and `y` are :class:`NumericProperty`s, we can create a
:class:`ReferenceListProperty` for the `pos`. If you change the value of
`pos`, it will automatically change the values of `x` and `y` accordingly.
If you read the value of `pos`, it will return a tuple with the values of
`x` and `y`.
'''
def __cinit__(self):
self.properties = list()
def __init__(self, *largs, **kw):
for prop in largs:
self.properties.append(prop)
Property.__init__(self, largs, **kw)
cdef init_storage(self, EventDispatcher obj, dict storage):
Property.init_storage(self, obj, storage)
storage['properties'] = self.properties
storage['stop_event'] = 0
cpdef link_deps(self, EventDispatcher obj, str name):
cdef Property prop
Property.link_deps(self, obj, name)
for prop in self.properties:
prop.bind(obj, self.trigger_change)
cpdef trigger_change(self, EventDispatcher obj, value):
cdef dict s = obj.__storage[self._name]
if s['stop_event']:
return
p = s['properties']
s['value'] = [p[x].get(obj) for x in xrange(len(p))]
self.dispatch(obj)
cdef convert(self, EventDispatcher obj, value):
if not isinstance(value, (list, tuple)):
raise ValueError('%s.%s must be a list or a tuple' % (
obj.__class__.__name__,
self.name))
return list(value)
cdef check(self, EventDispatcher obj, value):
if len(value) != len(obj.__storage[self._name]['properties']):
raise ValueError('%s.%s value length is immutable' % (
obj.__class__.__name__,
self.name))