Author: dmeyer
Date: Fri Apr 21 17:19:07 2006
New Revision: 1434
Modified:
trunk/base/src/weakref.py
Log:
better None support
Modified: trunk/base/src/weakref.py
==============================================================================
--- trunk/base/src/weakref.py (original)
+++ trunk/base/src/weakref.py Fri Apr 21 17:19:07 2006
@@ -35,6 +35,10 @@
from _weakref import ref
import types
+class NoneProxy(object):
+ def __call__(self):
+ return None
+
class weakref(object):
"""
This class represents a weak reference based on the python
@@ -43,6 +47,11 @@
E.g.: foo = weak(bar) and bar has the attribute x. With a normal
weakref.ref you need to call foo().x to get, this class makes it
possible to just use foo.x.
+
+ All functions are passed to the real object behind the weakref. To
+ check if the weakref is alive or not, you can compare the object with
+ None. Do not use a simple if, because an object still alive can also
+ be False (e.g. an empty list).
"""
def __new__(cls, object):
# Make an instance of callable weakref iff the object is callable.
@@ -59,17 +68,15 @@
else:
self._ref = ref(object)
else:
- self._ref = None
+ self._ref = NoneProxy()
-
def __getattribute__(self, attr):
- if attr == "__class__" and self:
+ if attr == "__class__":
return self._ref().__class__
if attr == "_ref":
return object.__getattribute__(self, attr)
- if self._ref:
- return getattr(self._ref(), attr)
-
+ return getattr(self._ref(), attr)
+
def __setattr__(self, attr, value):
if attr == "_ref":
return object.__setattr__(self, attr, value)
@@ -88,7 +95,7 @@
self._ref()[key] = value
def __nonzero__(self):
- if self._ref and self._ref():
+ if self._ref():
return 1
else:
return 0
@@ -99,14 +106,10 @@
return cmp(self._ref(), other)
def __str__(self):
- if self._ref:
- return "<weakref proxy; %s>" % str(self._ref())
- else:
- return 'weak reference to None'
+ return "<weakref proxy; %s>" % str(self._ref())
def __deepcopy__(self, memo):
- if self._ref:
- return weakref(self._ref())
+ return weakref(self._ref())
class _callable_weakref(weakref):
@@ -114,4 +117,4 @@
return super(weakref, weakref).__new__(cls)
def __call__(self, *args, **kwargs):
- return self._ref()(*args, **kwargs)
+ return self._ref()(*args, **kwargs)
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