Nested iteration?
Roy Smith
roy at panix.com
Tue Apr 23 11:40:31 EDT 2013
In reviewing somebody else's code today, I found the following
construct (eliding some details):
f = open(filename)
for line in f:
if re.search(pattern1, line):
outer_line = f.next()
for inner_line in f:
if re.search(pattern2, inner_line):
inner_line = f.next()
Somewhat to my surprise, the code worked. I didn't know it was legal
to do nested iterations over the same iterable (not to mention mixing
calls to next() with for-loops). Is this guaranteed to work in all
situations?
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