Marc 'BlackJack' Rintsch wrote: > 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. >
Why is it then that f (instance of Foo) really gets deleted? (__del__ is called) > Drop all those `__del__()` methods as they prevent the garbage collector > from collecting "cycles". > > Ciao, > Marc 'BlackJack' Rintsch I only inserted them so I can see if the objects are really freed. How can I see that without a __del__ method? Thanks so far, panzi -- http://mail.python.org/mailman/listinfo/python-list
