From d282b931a3d7b33fcddff15904b465ec8d54ba8f Mon Sep 17 00:00:00 2001
From: Raymond Hettinger <python@rcn.com>
Date: Sun, 28 Mar 2010 18:08:15 +0000
Subject: Add a note on optimizing the itertools recipes for production.

---
 Doc/library/itertools.rst | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/Doc/library/itertools.rst b/Doc/library/itertools.rst
index a978c1a..4f82a27 100644
--- a/Doc/library/itertools.rst
+++ b/Doc/library/itertools.rst
@@ -784,3 +784,9 @@ which incur interpreter overhead.
        except exception:
            pass
 
+Note, many of the above recipes can be optimized by replacing global lookups
+with local variables defined as default values.  For example, the
+*dotproduct* recipe can be written as::
+
+   def dotproduct(vec1, vec2, sum=sum, imap=imap, mul=operator.mul):
+       return sum(imap(mul, vec1, vec2))
-- 
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