[Python-3000] PEP Draft: Class Decorators

[Jack Diederich]

On Fri, Mar 09, 2007 at 06:19:49PM -0600, Collin Winter wrote:
> >History and Implementation
> >==========================
> >
> >Class decorators were originally proposed alongside function decorators
> >in PEP318 [1]_ and were rejected by Guido [2]_ for lack of use cases.
> >Two years later he saw a use case he liked and gave the go-ahead for a
> >PEP and patch [3]_.
> 
> I'd still prefer it if this use case -- which is so central to the PEP
> -- were provided in the PEP itself.

I'll make that more clear.  The use cas was factory registration right
next to the class definition (as opposed to afterwards or through a metaclass).
This is the example I use most frequently in the PEP.

> >Grammar/Grammar is changed from
> >
> >   funcdef: [decorators] 'def' NAME parameters ['->' test] ':' suite
> >
> >to
> >
> >    decorated_thing: decorators (classdef | funcdef)
> >    funcdef: 'def' NAME parameters ['->' test] ':' suite
> >
> >"decorated_thing"s are premitted everywhere that funcdef and classdef
> >are premitted.
> >
> >An alternate change to the grammar would be to make a 'decoratable_thing'
> >which would include funcdefs and classdefs even if they had no decorators.
> 
> Is it "decorated_thing" or "decoratable_thing"?

The current production is 'decorated_thing' because it requires at least one
decorator so it is definitely decorated.  If there are zero or more decorators
it would become 'decoratable_thing' as it would include the case where something
could be decorated but isn't.

Thanks, and I'll go typo hunting.

-Jack