[Python-Dev] thread-safe generator in standard library

[Tim Peters]

[Jewett, Jim J]
> ...
> The most obvious use case is to generate unique keys
> (as lisp gensym).

Just noting a practical hack that's often sufficient:

    import sys
    genunique = iter(xrange(sys.maxint)).next

Then each call to genunique() delivers "the next" (short) integer, and it
inherits thread safety from the global interpreter lock.

A similar effect can be gotten via

    import itertools
    genunique = itertools.count().next

and that also inherits thread safety from the GIL.

A difference is that the xrange spelling stops when it reaches sys.maxint,
but the .count spelling silently wraps around to -sys.maxint-1 then
(undetected overflow at the C level).