tac-tics wrote:
> Python is a crazy language when it comes to object versatility. I know
> I can do:
>
>>>> class test:
> ... def __init__(self):
> ... pass
>>>> x = test()
>>>> def fun():
> ... print "fun"
>>>> x.fun = fun
>>>> x.fun()
> fun
>
> However, experimenting shows that these attached functions are not
> bound to the object. They do not accept the 'self' parameter. I want to
> know how one goes about doing that. How do I bind a function to an
> object to act as if it were a method?
Functions are descriptors[1], and their __get__ method is used to bind
them to a particular instance::
>>> class test(object):
... def __init__(self):
... pass
...
>>> x = test()
>>> def fun(self):
... print "fun", self
...
>>> x.fun = fun.__get__(x, test)
>>> x.fun()
fun <__main__.test object at 0x00E6D730>
Note that calling __get__ returns a bound method, and that method can be
bound to an instance or a class depending on the parameters of __get__::
>>> fun.__get__(x, None)
<bound method ?.fun of <__main__.test object at 0x00E74510>>
>>> fun.__get__(x, test)
<bound method test.fun of <__main__.test object at 0x00E74510>>
>>> fun.__get__(None, test)
<unbound method test.fun>
[1] http://users.rcn.com/python/download/Descriptor.htm
STeVe
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