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From: rh <richard_hubbe11@lavabit.com>
Subject: regex walktrough
Date: Sat, 8 Dec 2012 09:48:13 -0800
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Xref: csiph.com comp.lang.python:34497

 Look through some code I found this and wondered about what it does:
^(?P<salsipuedes>[0-9A-Za-z-_.//]+)$

Here's my walk through:

1) ^ match at start of string
2) ?P<salsipuedes> if a match is found it will be accessible in a variable
salsipuedes
3) [0-9A-Za-z-_.//] this is the one that looks wrong to me, see below
4) + one or more from the preceeding char class
5) () the grouping we want returned (see #2)
6) $ end of the string to match against but before any newline


more on #3
the z-_ part looks wrong and seems that the - should be at the start
of the char set otherwise we get another range z-_ or does the a-z
preceeding the z-_ negate the z-_ from becoming a range?  The "."
might be ok inside a char set. The two slashes look wrong but maybe
it has some special meaning in some case? I think only one slash is
needed.

I've looked at pydoc re, but it's cursory.