[Python-Dev] Lexical scoping in Python 3k (original) (raw)

Josiah Carlson jcarlson at uci.edu
Mon Jul 3 08:08:33 CEST 2006

"Guido van Rossum" <guido at python.org> wrote:

On 7/3/06, Josiah Carlson <jcarlson at uci.edu> wrote: > > Greg Ewing <greg.ewing at canterbury.ac.nz> wrote: > > Josiah Carlson wrote: > > > If the only code that benefits from such changes are "very simple", > > > then I think that says something about its necessity. > > > > The point is that they're only "very simple" if you > > can write them using access to an outer scope. Without > > that ability, they become less simple, less efficient, > > more convoluted, harder to follow, etc. > > As is known and has been stated, assigning to a parent scope can be > emulated in various ways, either through an explicit namespace object, or > through a namespace list. And the fact that this desire and need remains, even amongst people who should know better, suggests that it may be worth supporting it more directly, as the current work-arounds ain't pretty.

Perhaps not pretty, but not wholly ugly either. Or expressed another way, it's a wart, but the wart isn't 1" across on a forehead, it's fairly small and tucked away on an elbow.

I had hoped that there would be a response to my second (and I believe more applicable statement); "if the feature is really only useful for generally trivial cases without the feature, then making them even more trivial, I think, is a bit of over optimization."

As for a solution, I find the "global means 'not local'" proposition is the least undesireable of the possibilities. It suffers from a change in semantics and potential name masking issues, but I don't believe these are any more serious than normal global masking for the former, and the latter is solvable with a future (at least for 2.6). I'm a solid -0 on this particular proposition, which is far better than the -1 I am on all of the other recent lexical scoping propositions.

More information about the Python-Dev mailing list