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Source code for kivy.weakmethod

Weak Method

The :class:`WeakMethod` is used by the :class:`~kivy.clock.Clock` class to
allow references to a bound method that permits the associated object to
be garbage collected. Please refer to
`examples/core/` for more information.

This WeakMethod class is taken from the recipe, based on the nicodemus version.
Many thanks nicodemus!

import weakref

[docs]class WeakMethod: '''Implementation of a `weakref <>`_ for functions and bound methods. ''' def __init__(self, method): self.method = None self.method_name = None try: if method.__self__ is not None: self.method_name = method.__func__.__name__ self.proxy = weakref.proxy(method.__self__) else: self.method = method self.proxy = None except AttributeError: self.method = method self.proxy = None def __call__(self): '''Return a new bound-method like the original, or the original function if it was just a function or unbound method. Returns None if the original object doesn't exist. ''' if self.proxy is not None: try: return getattr(self.proxy, self.method_name) except ReferenceError: return None return self.method
[docs] def is_dead(self): '''Returns True if the referenced callable was a bound method and the instance no longer exists. Otherwise, return False. ''' if self.proxy is None: return False try: getattr(self.proxy, self.method_name) return False except ReferenceError: return True
def __eq__(self, other): if type(self) is not type(other): return False s = self() return s is not None and s == other() def __repr__(self): return '<WeakMethod proxy={} method={} method_name={}>'.format( self.proxy, self.method, self.method_name)