[Python-Dev] Re: decorators and 2.4

[Phillip J. Eby]

At 04:27 PM 6/26/04 +0100, Paul Moore wrote:
>"Phillip J. Eby" <pje at telecommunity.com> writes:
>
> > * Which of the numerous possible syntax variations should be
> >   used/recommended:
>
>Just a reminder, but I believe that Guido has already pronounced to
>the effect that there are only 3 contenders left:

Those are based on changing the language's actual syntax.  The Dave 
Abrahams solution for decoration allows any currently-legal execution 
syntax to be used in today's Python versions.


>     @staticmethod
>     def foo(a,b,c):
>         pass
>
>     [staticmethod]
>     def foo(a,b,c):
>         pass
>
>and
>
>     def foo(a,b,c) [staticmethod]:
>         pass
>
>Hey - guess what? Writing them out like that, I find that my initial
>preference for the 3rd one has gone. To be honest, I no longer have a
>strong opinion between the three. In fact, if anything, I'd say I have
>a very mild preference for Guido's option (number 2). I dislike the
>ambiguity problem with it, though.

IMO, the ambiguity is resolved if some kind of visible invocation occurs, e.g.:

[declare_staticmethod()]
def foo(a,b,c):
     pass

While '[staticmethod]' by itself may appear to be a useless and ignorable 
statement, adding the () makes it clear that you have to know what the 
called function *does* before you could consider removing the statement.

When you add in the fact that this syntax can be made to work in Python 2.2 
and better, not just 2.4, it makes the syntax a big winner in my book.

I would like to reverse the application order, though: Guido's patch uses 
the same order for syntax 2 as for syntax 3, and now that I've played with 
syntax 2 "for real", I think that right-to-left application should be used 
for any syntax where the decorators come before the 'def'.