From: Raymond Hettinger <python@rcn.com>
Date: Fri, 6 Sep 2002 18:09:22 +0000 (+0000)
Subject: Added a tutorial note and example regarding the scope of loop variables
X-Git-Tag: v2.2.2b1~182
X-Git-Url: http://git.ipfire.org/gitweb.cgi?a=commitdiff_plain;h=4f976188454765080cf03d4d2ebfd4d58cca9573;p=thirdparty%2FPython%2Fcpython.git

Added a tutorial note and example regarding the scope of loop variables
in a list comprehension.  Includes a justification and a comparision
to regular for-loops.

Closes SF bug 605047.
---

diff --git a/Doc/tut/tut.tex b/Doc/tut/tut.tex
index 5c1e94b994a3..444e7d97c614 100644
--- a/Doc/tut/tut.tex
+++ b/Doc/tut/tut.tex
@@ -1862,6 +1862,19 @@ SyntaxError: invalid syntax
 [8, 12, -54]
 \end{verbatim}
 
+To make list comprehensions match the behavior of \keyword{for}
+loops, assignments to the loop variable remain visible outside
+of the comprehension:
+
+\begin{verbatim}
+>>> x = 100                     # this gets overwritten
+>>> [x**3 for x in range(5)]
+[0, 1, 8, 27, 64]
+>>> x
+4                               # the final value for range(5)
+>>
+\end{verbatim}
+
 
 \section{The \keyword{del} statement \label{del}}