[andreyf]

A closure is just a (function, bindings) pair, so Python certainly has closures. The problem with Python is that there is no syntax for assigning to variables declared in an arbitrary scope, because there are no explicit declarations. As far as I understand, implicit local variables are what causes the problems in Python, not anything about closures, really. This causes other problems, too, such as those PG described here [1], under the heading "Implicit local variables conflict with macros".

1. http://www.paulgraham.com/arclessons.html

[micheles]

Python 3 has read-write closures. Check out the nonlocal declaration.

[andreyf]

The nonlocal statement causes the listed identifiers to refer to previously bound variables in the nearest enclosing scope. [1]

While certainly a big improvement, we still can't access variables in arbitrary scopes, just local, nearest non-local, and global. To me, this seems a significantly more complex way of specifying variable scope than just declaring it explicitly.

1. http://docs.python.org/dev/3.0/reference/simple_stmts.html#t...

[mjs]

Interesting. Thanks.