[Python-Dev] closure semantics

[Guido van Rossum]

> [Alex]
> >>>So it can't be global, as it must stay a keyword for backwards
> >>>compatibility at least until 3.0.
> 
> [David]
> >>Why?  Removing keywords should be much simpler than adding them.  I
> >>have no idea how hard it is to hack the parser to adjust, but I
> >>can't imagine how having 'global' no longer be a keyword as far as
> >>its concerned break b/w compatibility.
> >>
> >>What am I missing?
> 
> [GvR]
> > I don't recall the context, but I think the real issue with removing
> > 'global' is that there's too much code out there that uses the global
> > syntax to remove the global statement before 3.0.
> 
[David]
> I would never have suggested that.  Just that we can evolve the parser
> to retain the old usage
> 
> 	global a,b,c
> 
> while allowing a new usage
> 
> 	global.a = value
> 
> by removing 'global' from the list of reserved words and doing "fancy
> stuff" in the parser.  Note that I very much don't know the details
> of the "fancy stuff".

Ah.  *If* we want to parse both it would be easier to keep global as a
keyword and do fancy stuff to recognize the second form...

But I think somewhere in the mega-thread about this topic is hidden
the conclusion that there are better ways to do this.

--Guido van Rossum (home page: http://www.python.org/~guido/)