73 lines
2.1 KiB
Python
73 lines
2.1 KiB
Python
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"""
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Weak Method
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===========
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The :class:`WeakMethod` is used by the :class:`~kivy.clock.Clock` class to
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allow references to a bound method that permits the associated object to
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be garbage collected. Please refer to
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`examples/core/clock_method.py` for more information.
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This WeakMethod class is taken from the recipe
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http://code.activestate.com/recipes/81253/, based on the nicodemus version.
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Many thanks nicodemus!
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"""
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import weakref
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class WeakMethod:
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'''Implementation of a
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`weakref <http://en.wikipedia.org/wiki/Weak_reference>`_
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for functions and bound methods.
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'''
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def __init__(self, method):
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self.method = None
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self.method_name = None
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try:
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if method.__self__ is not None:
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self.method_name = method.__func__.__name__
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self.proxy = weakref.proxy(method.__self__)
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else:
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self.method = method
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self.proxy = None
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except AttributeError:
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self.method = method
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self.proxy = None
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def __call__(self):
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'''Return a new bound-method like the original, or the
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original function if it was just a function or unbound
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method.
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Returns None if the original object doesn't exist.
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'''
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if self.proxy is not None:
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try:
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return getattr(self.proxy, self.method_name)
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except ReferenceError:
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return None
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return self.method
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def is_dead(self):
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'''Returns True if the referenced callable was a bound method and
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the instance no longer exists. Otherwise, return False.
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'''
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if self.proxy is None:
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return False
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try:
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getattr(self.proxy, self.method_name)
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return False
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except ReferenceError:
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return True
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def __eq__(self, other):
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if type(self) is not type(other):
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return False
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s = self()
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return s is not None and s == other()
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def __repr__(self):
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return '<WeakMethod proxy={} method={} method_name={}>'.format(
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self.proxy, self.method, self.method_name)
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