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authorRaymond Hettinger <python@rcn.com>2002-09-06 18:06:04 (GMT)
committerRaymond Hettinger <python@rcn.com>2002-09-06 18:06:04 (GMT)
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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.
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@@ -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}}