[Python-Dev] PEP 487 vs 422 (dynamic class decoration)

[PJ Eby]

On Fri, Apr 3, 2015 at 8:44 AM, Martin Teichmann
<lkb.teichmann at gmail.com> wrote:
> This proposal can actually be seen as an extension to the __class__
> and super() mechanism of normal methods: methods currently have the
> priviledge to know which classes they are defined in, while descriptors
> don't. So we could unify all this by giving functions a __post_process__
> method which sets the __class__ in the function body. This is about the
> same as what happened when functions got a __get__ method to turn
> them into object methods.
>
> While this all is in the making, PJ could monkey-patch __build_class__
> to do the steps described above, until it gets accepted into cpython.
> So I pose the question to PJ: would such an approach solve the
> problems you have?

Universal member post-processing actually works *better* for the
motivating use case than the metaclass or class level hooks, so yes.

In practice, there is one potential hiccup, and that's that decorators
which aren't aware of __post_process__ will end up masking it.  But
that's not an insurmountable obstacle.