[Python-3000] pyvm module - low level interface to Python's VM

[Phillip J. Eby]

At 04:52 PM 11/30/2007 +0000, Paul Moore wrote:
>On 30/11/2007, Barry Warsaw <barry at python.org> wrote:
> > >> class Example:
> > >>    implements(IExample)
> >
> > This frame hacking is also a pretty common feature of other types of
> > systems, such as ORMs.  It can make certain Python code much more
> > readable, so "frame hacking" is clearly a useful feature, at least it
> > seems, in the context of a class definition.  Is there a way to
> > promote this to an API that's more principled than the sys._getframe
> > () hack, and thus more acceptable to Guido and more portable to other
> > implementations?
> >
> > (Or is something like this already in Py3K, and I just haven't
> > noticed it yet? ;).
>
>There's class decorators:
>
>     @implements(IExample)
>     class Example:
>         pass
>
>which could provide the same result in effect, but (as J-P points out)
>it's still an API change and so not a direct replacement. IIRC, one of
>the arguments for class decorators was that they are a way to avoid
>the need for some of this getframe hacking, though.

Well, for what class-level frame hacking is typically used for, it 
would suffice to have a convenient way to refer to the local 
namespace, e.g. if you could do something like:

     implements(@, IExample)

where @ was a shortcut for locals().  The most-used frame hacks (in 
zope.interface and most PEAK tools) just want to access the namespace 
of the current class definition, and maybe decorate the class in some way.