[Python-Dev] Submitting PEP 422 (Simple class initialization hook) for pronouncement

[Daniel Urban]

On Sun, Feb 10, 2013 at 5:48 PM, Stefan Behnel <stefan_ml at behnel.de> wrote:
> However, it's hard to say if this "new way of doing it" doesn't come with
> its own can of worms. For example, would cooperative calls to
> "__init_class__" work if a superclass already defines it? Do implementors
> have to remember that? And is it clear how this should be done, e.g. what
> should normally go first, my own code or the superclass call? Supporting
> cooperative __init_class__() calls properly might actually be a good thing.
> Currently, there's only one metaclass, plus a sequence of decorators, which
> makes the setup rather static and sometimes tedious for subclasses that
> need to do certain things by themselves, but in addition to what happens
> already.

Cooperative multiple inheritance of __init_class__ would work exactly
the same way as it works e.g., for __init__ of any other method
(actually it is easier, since as Nick mentioned, the signature is
always the same): __init_class__ can simply use the zero argument form
of super. There is a simple example in the tests at
http://bugs.python.org/issue17044.


Daniel