how to dynamically instantiate an object inheriting from several classes?
Arnaud Delobelle
arnodel at googlemail.com
Fri Nov 21 17:30:16 EST 2008
Joe Strout <joe at strout.net> writes:
> I have a function that takes a reference to a class, and then
> instantiates that class (and then does several other things with the
> new instance). This is easy enough:
>
> item = cls(self, **itemArgs)
>
> where "cls" is the class reference, and itemArgs is obviously a set of
> keyword arguments for its __init__ method.
>
> But now I want to generalize this to handle a set of mix-in classes.
> Normally you use mixins by creating a class that derives from two or
> more other classes, and then instantiate that custom class. But in my
> situation, I don't know ahead of time which mixins might be used and
> in what combination. So I'd like to take a list of class references,
> and instantiate an object that derives from all of them, dynamically.
>
> Is this possible? If so, how?
Of course it's possible: use type(name, bases, dict).
>>> class A(object): pass
...
>>> class B(object): pass
...
>>> C = type('C', (A, B), {})
>>> issubclass(C, A)
True
>>> issubclass(C, B)
True
Call-by-object'ly yours
--
Arnaud
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