[Python-ideas] generic Liftable abc-mixin breaks at MRO

[M.-A. Lemburg]

On 10.12.2015 09:58, Stephan Sahm wrote:
> Dear all,
> 
> I think I found a crucial usecase where the standard MRO does not work out.
> I would appreciate your help to still solve this usecase, or might MRO even
> be adapted?
> 
> The idea is to build a generic Lift-type which I call this way because the
> derived classes should be able to easily lift from subclasses. So for
> example if I have an instance *a* from *class A* and a *class B(A)* I want
> to make *a* an instance of *B* in a straightforward way.

Why don't you use:

a.__class__ = B

?

>>> class A: pass
...
>>> class B(A): pass
...
>>> a = A()
>>> a
<__main__.A instance at 0x7f0bf5ccdc68>
>>> a.__class__ = B
>>> a
<__main__.B instance at 0x7f0bf5ccdc68>
>>>

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