moving methods from class to instance of other class

[Benjamin Kaplan]

On Wed, Jun 27, 2012 at 11:59 PM, lars van gemerden
<lars at rational-it.com> wrote:
> Hi all,
>
> I have some trouble with the following question: Let say i have the
> following classes:
>
> class A(object):
>    def __init__(self):
>        self.name = 'a'
>    def do(self):
>        print 'A.do: self.name =', self.name
>
> class B(object):
>    def __init__(self):
>        self.name = 'b'
>
>
>
> The question is: How do i move the 'do' method from A to b (resulting
> in  printing "A.do: self.name = b")?
>
> I have tried (with a = A() and b  B()):
>
> B.do = types.MethodType(A.do, b) #Error
>
> and stuff like:
>
> b.do = a.do
> b.do()
>
> But either i get an error or b.do() prints  "A.do: self.name = a", so
> the self parameter of a.do is stored somehow in the method.
>
> In other words, how do i unbind 'do' from a/A and bind it to b (the
> instance)?
>
> Cheers, Lars
>

Is there any particular reason you can't just have B be a subclass of
A? You could do

b.do = types.MethodType(A.do.im_func, b, B)

but there's no point in re-inventing the wheel.