[Python-Dev] Re: new syntax for wrapping (PEP 318)

[Phillip J. Eby]

At 11:35 AM 2/26/04 -0500, Jewett, Jim J wrote:
>Pete Shinners:
> > Some of these may even be bad ideas apon further
> > thought, but it's something to ponder.
>
>Also, many of them don't work with the proposed
>syntax.  Specifically, you're trying to provide
>a second binding for the function (such as running
>for __main__, or registering with the exit handler).

def __main__(func):
     if __name__=='__main__':
         func()

This now works correctly as long as you define your main function as the 
last thing in your module.

As for the exit handler thing, that works okay too.  All that happens is 
that the function you decorate it as will be None.  So after:

def exitHandler() [atexit.register]:
     ...

'exitHandler' will be 'None', but the function as it was defined will be 
registered for running at system exit.

So, yes, actually, these two ideas do work with the proposed syntax.


>Features which are used frequently need to be short.
>Features which are used rarely (like this one?) can be
>more verbose.

Actually, I think that if the feature exists, it will be used frequently 
and for a wide variety of things.  It is probably the closest thing to 
having macros that Python will ever get.  We don't even know how many other 
cool things people will come up with to do with them.


>I agree that if only advanced users will need it, then it
>can be a bit more complex to use.

Advanced users will *create* decorators, but everybody will want to *use* them.


>If you use bare syntax, then the burden is
>on everyone, and you have raised the barrier to entry for
>the rest of the language.

I don't think that's true, even for the [] syntax case.  Most decorator 
lists will be relatively short, and the items *in* the decorator list will 
almost always be a good place to look them up.  It's only the reuse of 
non-decorators (like 'atexit.register') or undocumented custom decorators 
that's likely to be confusing in reading code.