On Sun, 07 Oct 2007 16:51:33 +0200, Mathias Panzenboeck wrote:
> import weakref
>
> class Wrapper(object):
> def __init__(self,x):
> self.x = weakref.ref(x)
>
> def __call__(self,*args,**kwargs):
> x = self.x()
> if x is None:
> print "lost reference"
> else:
> return x(*args,**kwargs)
>
> class Foo(object):
> def __init__(self):
> self._methods = set()
> self._methods.add(Wrapper(self._foo))
>
> def _foo(self):
> print "_foo"
>
> def callMethods(self):
> for method in self._methods:
> method()
>
> def __del__(self):
> print "del Foo"
>
> class Bar(object):
> def __init__(self):
> self._methods = set()
> self._methods.add(self._foo)
>
> def _foo(self):
> print "_foo"
>
> def callMethods(self):
> for method in self._methods:
> method()
>
> def __del__(self):
> print "del Bar"
>
>
>
> Now look what happens when I do this:
>
>>>> f=Foo()
>>>> f.callMethods()
> lost reference
>>>> del f
> del Foo
>>>> b=Bar()
>>>> b.callMethods()
> _foo
>>>> del b
>>>>
>
> Foo looses the reference to its method but Bar on the other hand has a
> refloop and
> never gets deleted.
``del b`` just deletes the name `b`. It does not delete the object.
There's still the name `_` bound to it in the interactive interpreter.
`_` stays bound to the last non-`None` result in the interpreter.
Drop all those `__del__()` methods as they prevent the garbage collector
from collecting "cycles".
Ciao,
Marc 'BlackJack' Rintsch
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