[Python-Dev] Issues with PEP 526 Variable Notation at the class level

[Antoine Pitrou]

On Sun, 10 Dec 2017 20:47:45 +0100
Antoine Pitrou <solipsis at pitrou.net> wrote:

> Hi,
> 
> On Sun, 10 Dec 2017 19:17:25 +0000
> Tin Tvrtković <tinchester at gmail.com> wrote:
> > Hello,
> > 
> > I'm one of the attrs contributors, and the person who initially wrote the
> > slots functionality there.
> > 
> > We've given up on returning a new class always since this can conflict with
> > certain metaclasses (have you noticed you can't make a slots attrs class
> > inheriting from Generic[T]?) and with PEP 487. I think with PEP 487 it's
> > becoming especially evident class creation is not necessarily an idempotent
> > operation.  
> 
> Hmm... I understand you may be restricted by backwards compatibility
> here.  But dataclasses don't have that issue, so we could decide we're
> incompatible with certain dataclasses from day 1.

Sorry... make that "incompatible with certain metaclasses" ;-)

Regards

Antoine.