Swapping superclass from a module

Emanuele D'Arrigo manu3d at gmail.com
Sun May 17 00:35:31 CEST 2009

On May 16, 8:17 pm, Arnaud Delobelle <arno... at googlemail.com> wrote:
> # Insert Wedge into each subclass of modfoo.Base
> for subclass in modfoo.Base.__subclasses__():
>     if subclass.__module__ != 'modfoo': continue
>     attrs = dict(item for item in subclass.__dict__.items()
>                       if item[0][:2] != '__')
>     name = subclass.__name__
>     setattr(modfoo, name, type(name, (Wedge,), attrs))
> # Replace modfoo.Base with Wedge
> modfoo.Base = Wedge

That-is-neat! I'm impressed. It took me a while to understand it all:
I didn't know about __subclasses__, the way you fill the dictionary is
completely novel to me and the use of type(name, tuple, attributes)
was also completely novel to me. But eventually I got it and it's
quite neat. Thank you.

> Of course, there are plenty of ways this could break.

Uh-oh. Ok, you got me all excited and now I have to read the fine
prints. So, how can it break?



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