[Python-checkins] r79483 - python/trunk/Doc/library/itertools.rst

[raymond.hettinger]

Author: raymond.hettinger
Date: Sun Mar 28 20:25:01 2010
New Revision: 79483

Log:
Update itertools recipe for consume().

Modified:
   python/trunk/Doc/library/itertools.rst

Modified: python/trunk/Doc/library/itertools.rst
==============================================================================
--- python/trunk/Doc/library/itertools.rst	(original)
+++ python/trunk/Doc/library/itertools.rst	Sun Mar 28 20:25:01 2010
@@ -672,7 +672,13 @@
 
    def consume(iterator, n):
        "Advance the iterator n-steps ahead. If n is none, consume entirely."
-       collections.deque(islice(iterator, n), maxlen=0)
+       # Use functions that consume iterators at C speed.
+       if n is None:
+           # feed the entire iterator into a zero-length deque
+           collections.deque(iterator, maxlen=0)
+       else:
+           # advance to the emtpy slice starting at position n
+           next(islice(iterator, n, n), None)
 
    def nth(iterable, n, default=None):
        "Returns the nth item or a default value"