On 3/27/06, Phillip J. Eby wrote:

PyProtocols and the zope.interface package both support inline class decorators called "class advisors". They don't require any special syntax, and aren't much more complex than regular decorators. By defining an advisor like this:

from protocols.advice import addClassAdvisor

def some_advisor(whatever_args): def callback(cls): print "I can modify",cls,"or replace it" return cls addClassAdvisor(callback)

you can then use it in a class body like so:

class SomeClass: some_advisor("something")

And the return value from 'callback' will replace SomeClass, just like a decorator replaces the function it's called on.

The implementation should work with any Python version from 2.2 up. I'm not sure if it would work with IronPython. But if it doesn't, that would be a good indication of feature(s) that IronPython is missing. ;)

Just curious (and lazy): what magic is the implementation using that makes this work without a custom metaclass? -- --Guido van Rossum (home page: http://www.python.org/~guido/)

On 3/28/06, Samuele Pedroni wrote:

Mike Krell wrote:

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Greg Ewing writes:

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I've just been playing around with metaclasses, and I think I've stumbled across a reason for having class decorators as an alternative to metaclasses for some purposes.

There has also been discussion on the IronPython mailing list that class decorators would be a very useful syntax for expressing .NET attributes.

http://lists.ironpython.com/pipermail/users-ironpython.com/2006-March/002007...

the same is true for Jython and Java annotations.

OK, I'm convinced (mostly by the awful hackery that Phillip so proudly exposed :-). I propose that someone start writing a Py3k PEP for class decorators. I don't think it's fair to the 2.5 release team to want to push this into 2.5 though; how about 2.6? -- --Guido van Rossum (home page: http://www.python.org/~guido/)

On Tue, Mar 28, 2006 at 10:16:01AM -0800, Neal Norwitz wrote:

On 3/28/06, Guido van Rossum wrote:

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I propose that someone start writing a Py3k PEP for class decorators. I don't think it's fair to the 2.5 release team to want to push this into 2.5 though; how about 2.6?

Wasn't there already a (pretty small) patch? I guess it would be different now with the AST though.

I submitted one a couple years ago. The AST makes it obsolete though. I'd be happy to make a new AST friendly one (time to learn the AST..) -Jack