Talin wrote:
> I propose to create a new type of scoping rule, which I will call
> "explicit" lexical scoping, that will co-exist with the current
> "implicit" scoping rule that exists in Python today.
I'd like to toss one more variant into the mix. If we really need to
address variables in an intermediate scope, the most explicit way that I
can think of doing so is to write (using Philip's example):
def counter(num):
scope as outer # "outer" is an arbitrary identifier
def inc():
outer.num += 1
return outer.num
return inc
Why not extend the interface to the locals builtin and add a __getitem__ that returns a proxy to access locals defined in other lexical scopes via __{get/set/del}attr_:
def counter(num):
num = 1
def inc():
locals[1].num += 1
return outer.num
return inc
Where, for CPython, locals[n] gives access to NamespaceProxy(sys._getframe(n).f_locals). In addition to having a relatively pleasing and explicit syntax, this may be a feasible method for allowing portable introspection into outer scopes without having to export the whole frame object a la sys._getframe(n). I strongly suspect that Jython, IronPython, and PyPy would have little difficulty supporting (and optimizing) this construct.
Lacking core language support, it is easy to roll an object that does just what I suggest. Actual implementation is left to a more motivated reader, of course.
Just another crazy idea to throw into the pot.
-Kevin
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