[Python-Dev] Possible resolution of generator expression variable capture dilemma (original) (raw)

Guido van Rossum guido at python.org
Wed Mar 24 11:24:43 EST 2004

Phillip shows some examples involving inner functions defined inside the for loop. But in current Python these examples work just as well if the function is defined outside the loop (as long as no default argument values are needed):

for x in 1,2,3: def y(): print z z = x * 2 y()

is the same as

def y(): print z for x in 1, 2, 3: z = x*2 y()

That would change under Phillip's proposal.

There are similar examples that would break under Greg's original proposal: just use the loop variable in the function, e.g.:

def y(): print x*2 for x in 1, 2, 3: y()

All this is just more reason to put this one off until 3.0.

--Guido van Rossum (home page: http://www.python.org/~guido/)

More information about the Python-Dev mailing list