"Steve Holden" <[EMAIL PROTECTED]> wrote in message news:[EMAIL PROTECTED] | Micah Cowan wrote: | > "Jerry Hill" <[EMAIL PROTECTED]> writes: | > | >> On Fri, Feb 29, 2008 at 10:01 PM, Ken Pu <[EMAIL PROTECTED]> wrote: | >>> Is there a way for me keep the iterating variable in list | >>> comprehension local to the list comprehension? | >> Kind of. You can use a generator expression instead of a list | >> comprehension, and those don't leak their internal variables into the | >> enclosing scope: | > | > Whoa, that's cool. I didn't even think to try that, just assuming it | > would do the same. | > | > Though now that I think about it, I don't see how it possibly could, | > since it just evaluates to an object that you could pass around, and | > return, using it the same way elsewhere. | > | Well, the fact that the bound variable in the list comprehension does | indeed remain outside the construct is simply the result of an | over-zealous wish to emulate for loop semantics. The original reasoning, | IIRC, as that since a for loop left its bound variable at the last used | value, so should a list comprehension. | | This was quickly recognized as a mistake, but unfortunately not quickly | enough. As it was felt that some people might already have relied on | that behavior, it was retained in the interests of preserving backwards | compatibility.
But it will not be retained in 3.0, as I understand it. So best to not exploit the deprecated behavior. tjr -- http://mail.python.org/mailman/listinfo/python-list
