[Python-ideas] PEP 560 (second post)

Koos Zevenhoven k7hoven at gmail.com
Fri Nov 10 12:39:08 EST 2017

On Wed, Sep 27, 2017 at 12:28 PM, Ivan Levkivskyi <levkivskyi at gmail.com>

> Previously I posted PEP 560 two weeks ago, while several other PEPs were
> also posted, so it didn't get much of attention. Here I post the PEP 560
> again, now including the full text for convenience of commenting.

> After creating the class,
> the original bases are saved in ``__orig_bases__`` (currently this is also
> done by the metaclass).
​Those are *still* bases, right, even if they are not in the mro?​ I'm not
sure if this is a naming thing or something even more.

> NOTE: These two method names are reserved for exclusive use by
> the ``typing`` module and the generic types machinery, and any other use is
> strongly discouraged.

​Given the situation, that may be a good thing. But will it really work? I
think it is also strongly discouraged to invent your own dunder method
names, but people still do it.​

> The reference implementation (with tests) can be found
> in [4]_, the proposal was originally posted and discussed on
> the ``typing`` tracker, see [5]_.
> Backwards compatibility and impact on users who don't use ``typing``:
> =====================================================================
> This proposal may break code that currently uses the names
> ``__class_getitem__`` and ``__subclass_base__``.



+ Koos Zevenhoven + http://twitter.com/k7hoven +
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