[Python-Dev] statically nested scopes

[Guido van Rossum]

> Well first you'd have to change all tools to use the new
> scheme (this includes debuggers, inspection tools, reflection
> kits, etc.). This certainly is not a smart thing to do since
> Python IDEs are just starting to appear -- you wouldn't want
> to break all those.

I've seen a Komodo demo.  Yes, it does this.  But it's soooooooo far
from being done that adding this wouldn't really slow them down much,
I think.  More likely, the toolmakers will have fun competing with
each other to be the first to support this! :-)

> What get's harder with the nested scheme is that
> you can no longer be certain that globals() reaches out to
> the module namespace. But this is needed by some lazy evaluation
> tools. Writing to globals() would not be defined anymore --
> where should you bind the new variable ?

I think globals() should return the module's __dict__, and the global
statement should cause the variable to reach directly into there.

We'll need to introduce a new builtin to do a name *lookup* in the
nested scopes.

> Another problem is that there probably won't be a way to access
> all the different nesting levels on a per-level basis (could be
> that I'm missing something here, but debugging tools would need
> some sort of scope() builtin to access the different scopes).
> I'm not sure whether this is possible to do without some sort
> of link between the scopes. We currently don't need such links.

Correct.  That link may have to be added to the frame object.

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