Amit Dev wrote:
> Simple question. If I have the following code:
>
> class A:
> def __init__(self, s):
> self.s = s
> self.m2 = m1
>
> def m1(self):
> pass
>
> if __name__ == '__main__':
> a = A("ads")
> a.m1()
> a = None
>
> The object is not garbage collected, since there appears to be a cycle
> (between method m2 and A). I would expect this to behave the same as
> having another method "def m2(self): self.m1()", but unfortunately its
> not.
> In above case m2 seems to be in a.__dict__ which is causing the cycle.
> Any idea why this is so?
Hm, I get a NameError
Traceback (most recent call last):
File "tmp.py", line 10, in <module>
a = A("ads")
File "tmp.py", line 4, in __init__
self.m2 = m1
NameError: global name 'm1' is not defined
In general self.some_method returns a bound method which holds a reference
to both the some_method function and the instance:
>>> class A:
... def m(self): print "M"
...
>>> a = A()
>>> am = a.m
>>> am.__self__, am.__func__
(<__main__.A instance at 0x7f91c040e638>, <function m at 0x7f91c03f8b18>)
Therefore something like a.mm = a.m will create a reference cycle.
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