metaclass and customization with parameters

Andrew Durdin adurdin at gmail.com
Wed Oct 6 01:35:01 CEST 2004


On Tue, 5 Oct 2004 18:57:49 -0300, Gustavo Niemeyer
<niemeyer at conectiva.com> wrote:
> 
> That's not true. The def statement is rerun every loop, no matter
> what parameters are used. One can check that by issuing:
> 
> print MyClass.method0.im_func
> print MyClass.method1.im_func

Hmmm... If I create MyClass as above, I get the following results
which I don't understand:

>>> mc = MyClass()
>>> id(mc.method0)
9343264
>>> id(mc.method1)
9343264
>>> mc.method0
<bound method MyClass.newmethod of <__main__.MyClass instance at 0x008E93A0>>
>>> mc.method1
<bound method MyClass.newmethod of <__main__.MyClass instance at 0x008E93A0>>
>>> mc.method0.im_func
<function newmethod at 0x008E7730>
>>> mc.method1.im_func
<function newmethod at 0x008EC0F0>
>>> id(mc.method0.im_func)
9336624
>>> id(mc.method1.im_func)
9355504

Why do mc.method0 and mc.method1 appear to be the same object?

Even more confusing to me is:

>>> class Foo:
...     def method0(self):
...             pass
...     def method1(self):
...             pass
...     def method2(self):
...             pass
...
>>> Foo.method0
<unbound method Foo.method0>
>>> Foo.method1
<unbound method Foo.method1>
>>> Foo.method2
<unbound method Foo.method2>
>>> f = Foo()
>>> id(f.method0)
9345304
>>> id(f.method1)
9918464
>>> id(f.method2)
9918464

Here f.method1 and f.method2 share the same id, which is different to
that of f.method1...

Can anyone enlighten me as to why this happens?



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