[pypy-commit] pypy.org extradoc: Add a paragraph "Abuse of itertools".

[arigo]

Author: Armin Rigo <arigo at tunes.org>
Branch: extradoc
Changeset: r327:aa71b020271b
Date: 2012-02-13 10:15 +0100
http://bitbucket.org/pypy/pypy.org/changeset/aa71b020271b/

Log:	Add a paragraph "Abuse of itertools".

diff --git a/source/performance.txt b/source/performance.txt
--- a/source/performance.txt
+++ b/source/performance.txt
@@ -68,6 +68,15 @@
   sometimes not. In most cases (like ``csv`` and ``cPickle``), we're slower
   than cPython, with the notable exception of ``json`` and ``heapq``.
 
+* **Abuse of itertools**: The itertools module is often "abused" in the
+  sense that it is used for the wrong purposes.  From our point of view,
+  itertools is great if you have iterations over millions of items, but
+  not for most other cases.  It gives you 3 lines in functional style
+  that replace 10 lines of Python loops (longer but arguably much easier
+  to read).  The pure Python version is generally not slower even on
+  CPython, and on PyPy it allows the JIT to work much better --- simple
+  Python code is fast.
+
 We generally consider things that are slower on PyPy than CPython to be bugs
 of PyPy.  If you find some issue that is not documented here,
 please report it to our `bug tracker`_ for investigation.