[Andrew Koenig]
I saw messages out of sequence and did not realize that this would be a change in behavior from 2.4. Sigh.
[Ka-Ping Yee]
Yes, this is not a good time to change it.
I hope Py3000 has lexical scoping a la Scheme...
Me too -- that would be really nice.
[Guido]
That's not a very constructive proposal (especially since I don't know Scheme). Perhaps you could elaborate on what needs to change?
It's effectively the opposite of Python <0.1 wink>: a name is local to a scope in Scheme if and only if a declaration says it is. For example, the "let" family of forms is often used for this purpose, and (let ((x 2) (y 3)) # declares x and y as local to this `let`, and gives initial values (let ((x 7) (z (+ x y))) # x comes from outer `let` so is 2, and z is 2+3=5 (* z x))) # x comes from inner `let`, so this is 5*7=35 If you use `let*` instead of `let` in the inner one, z picks up the inner x=7, so that z is 7+3=10, and the result is 7*10 = 70 instead. The bindings in a `let` "happen" in an undefined order. In `let*`, a binding is visible "to its right" within the `let*`. Then there's `letrec`, which allows establishing mutually recursive bindings. While the `let` family is entirely about declaration, there are lots of other forms that mix in some declaration as part of their purpose (for example, the names in a lambda's argument list are local to the lambda's body), but they're all explicit in Scheme. I read "a la Scheme" here as "actually nothing like Scheme, except I want a non-tricky way to rebind a name from an enclosing scope within an enclosed scope". In Scheme, the scope a name x belongs to is found by searching enclosing scopes until you hit the first with an explicit "x belongs to me" declaration (OK, there's a hokey fallback to "top level" definitions too). Searching "textually up" always suffices (there's no form of delayed declaration -- a name must be declared before use). Scheme's assignment of assignment: (set! variable expression) has nothing to do with establishing the scope of `variable`.