Velocity Reviews - Computer Hardware Reviews

Velocity Reviews > Newsgroups > Programming > Python > re module substitution confusion

Thread Tools

re module substitution confusion

Doug Farrell
Posts: n/a
Hi all,

I'm trying to do the following from within a code module:

import re

# text to match
text = "Good morning x something /x, how are you today x something
else /x"

# pattern to match
regex = re.compile("(x)(.*?)(/x)", re.DOTALL)

# find first match
m =, text)

# keep looking while there are matches
while m != None:
# substitute in some other text for the exact match
text = re.sub(, "Mr. Phelps", text)

# find the next match
m =, text)

print text

This works within the Python shell, but I can't seem to make it work
from within a program. It would seem like the re.sub(
would work fine as just returns the matched string

Any help would be greatly appreciated,
Doug Farrell
Reply With Quote
Doug Farrell
Posts: n/a
Hi all,

I got a direct email from someone (who I can't remember right now) who
suggested that I wasn't very clear about what I was trying to do and
what was wrong. In an attempt to clarify I'm adding this post.

I'm trying to create a little Python CGI program that will read in a
HTML template file that has Python code embedded in it between
<python> ... </python> tags. So I'd like to use the re module to find
the following pattern:

pattern = re.compile("(<python>)(.*?)(</python>)", re.DOTALL)

Doing a search with this pattern like this:

match =, text)

where text equals the HTML template file in string form, will find all
the code segments. I then pull out the code segment and pass it to
exec() to execute it. I can capture the output of the exec() call by
redirecting sys.stdout to a StringIO object. The problem is that this;
I can match the <python>...</python> segments no problem. But I only
want to replace each one in turn with the results of the exec() call.
If I do this:

text = re.sub(pattern, ".. exec() output..", text) it replaces all the
code segments, not just the one that was matched. I need to substitute
in the output of the exec() (which is a string when I'm done) into the
one place it came from.

Hope this clears up any confusion.

I didn't include the whole program in my first post as it's kind of
long. I thought the sections I included above were enough information
to follow what I'm trying to do, at least I hope so.

Thanks again in advance for your help,
Reply With Quote

Thread Tools

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are Off

Similar Threads
Thread Thread Starter Forum Replies Last Post
module confusion rjcarr Python 46 10-06-2007 06:28 AM
Re: module docstring, documentation,anything? please note is the module type/object NOT some module Maric Michaud Python 0 06-24-2006 12:42 PM
Module to handle substitution in error messages? Henry Law Perl Misc 7 11-20-2005 09:04 PM
semi-newbie module namespace confusion Python 6 10-07-2005 08:01 AM
Catalyst 6k Series Module Confusion Mike Hanson Cisco 3 03-07-2004 06:20 PM