Table Of Contents
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/clock_method.py` for more information.
This WeakMethod class is taken from the recipe
http://code.activestate.com/recipes/81253/, based on the nicodemus version.
Many thanks nicodemus!
"""
import weakref
[docs]class WeakMethod:
'''Implementation of a
`weakref <http://en.wikipedia.org/wiki/Weak_reference>`_
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)
