[Python-Dev] pep 318, Decorators for Functions, Methods and Classes (original) (raw)

Jack Diederich jack at performancedrivers.com
Wed Aug 11 21:44:44 CEST 2004

On Tue, Aug 10, 2004 at 09:11:16PM -0400, Jack Diederich wrote:

On Sat, Aug 07, 2004 at 02:05:14PM -0700, Guido van Rossum wrote: > > I just wanted to say that I believe it should be allowed to decorate > > classes. There's not reason enough (reading the thread linked to by the > > PEP) to limit decorators this way. Like said several times in that > > thread, metaclasses are harder (to write and to understand) than > > decorators. > > Are you volunteering to implement it? > I'm game, I would prefer to use class decorators in most of the places I currently use metaclasses.

I have a mostly working patch for class decorators but it gets an XXX ambiguity between

funcdef: [decorators] 'def' NAME parameters ':' suite and classdef: [decorators] 'class' NAME [ '(' testlist ')' ] ':' suite

It works as advertised with the pre-decorators funcdef definition (which removes the ambiguity). Help?

-Jack

--- quicktst.py ----

class Tom(object): pass

def decor(cls): print "decord'd", cls return Tom

@decor class Dick(object): """ some classs """ def bar(self): print "BAR!" return

@decor class Harry: def bar(self): print "BAR!" return

print Dick print Dick.class print Harry print Harry() print Harry().bar()

./python Python 2.4a2 (#13, Aug 11 2004, 15:25:00) [GCC 3.3.4 (Debian 1:3.3.4-4)] on linux2 Type "help", "copyright", "credits" or "license" for more information.

import quicktst decord'd <class 'tst.Dick'> decord'd tst.Harry <class 'tst.Tom'> <type 'type'> <class 'tst.Tom'> <tst.Tom object at 0x402c23ec> Traceback (most recent call last): File "", line 1, in ? File "tst.py", line 25, in ? print Harry().bar() AttributeError: 'Tom' object has no attribute 'bar'

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