Doing both regex match and assignment within a If loop?

Victor Hooi victorhooi at
Fri Mar 29 05:00:44 CET 2013


I have logline that I need to test against multiple regexes. E.g.:

    import re

    expression1 = re.compile(r'....')
    expression2 = re.compile(r'....')

    with open('log.txt') as f:
        for line in f:
            if expression1.match(line):
                # Do something - extract fields from line.
            elif expression2.match(line):
                # Do something else - extract fields from line.
                # Oh noes! Raise exception.

However, in the "Do something" section - I need access to the match object itself, so that I can strip out certain fields from the line.

Is it possible to somehow test for a match, as well as do assignment of the re match object to a variable?

    if expression1.match(line) = results:

Obviously the above won't work - however, is there a Pythonic way to tackle this?

What I'm trying to avoid is this:

    if expression1.match(line):
        results = expression1.match(line)

which I assume would call the regex match against the line twice - and when I'm dealing with a huge amount of log lines, slow things down.


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