[Python-Dev] @decoration of classes (original) (raw)

Jp Calderone exarkun at divmod.com
Sat Mar 26 23:16:49 CET 2005

On Sat, 26 Mar 2005 22:49:33 +0100, Eric Nieuwland <eric.nieuwland at xs4all.nl> wrote:

On 26 mrt 2005, at 21:36, Josiah Carlson wrote: > Eric Nieuwland <eric.nieuwland at xs4all.nl> wrote: >> Given the ideas so far, would it possible to: >> >> def meta(cls): >> ... >> >> @meta >> class X(...): >> ... > > It is not implemented in Python 2.4. From what I understand, making it > happen in Python 2.5 would not be terribly difficult. The question is > about a "compelling use case". Is there a use where this syntax is > significantly better, easier, etc., than an equivalent metaclass? > Would > people use the above syntax if it were available? > > What would you use the above syntax to do?

Well, I can imagine using @meta(MyMetaClass) class MyClass(...): ... instead of class MyClass(...): metaclass = MyMetaClass ... Somehow, it seems more aesthetic to me.

This doesn't quite work the same, though. The former creates a new instance of ClassType, then (presumably) rips it apart and passes the pieces to MyMetaClass.

The latter just passes the pieces to MyMetaClass unassembled.

I can imagine cases where the class creation would fail during the first step of the former process, so I don't think this is actually a use-case for class decorators.

Jp

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