73 lines
2.1 KiB
Python
73 lines
2.1 KiB
Python
"""
|
|
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
|
|
|
|
|
|
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
|
|
|
|
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)
|