Re^3: regex: extract multiple number of date patterns from certain lines

So, if I understand this correctly, you are saying that my code works, but there is some constraint that it has to be in one single regex? If that's the case, then we are into some obfuscated code problem and this is perhaps the wrong place?

If we are talking about clarity and performance, then that's different. Fewer lines of Perl code doesn't always equal faster performance. I simplified this stuff like must match exactly 4 times, etc. This speeds up the regex engine. As far as clarity goes, I would struggle to be more clear (I'm not a guru).

If you are interested in performance, then measure and test performance (run benchmarks).

Counting the number of lines of source code is a relatively poor predictor of actual code performance.

Update: Well it just took some few seconds to get a negative vote on this post. I was genuinely trying to help with the original problem. I don't understand this requirement for "one line". I think that benchmarking and testing is the right way to go. I would be happy to help in this regard.

Comment on Re^3: regex: extract multiple number of date patterns from certain lines

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Re^4: regex: extract multiple number of date patterns from certain lines by Random_Walk (Prior) on Mar 05, 2009 at 06:34 UTC
Hi Marshall There is actually a constraint that it has to be a single regex, see my answer to Ikegami at Re^2: regex: extract multiple number of date patterns from certain lines to see more of the context in which I am operating. As for XP, I did not vote you down but there are some grumpy monks around with itchy trigger fingers, I got -- for every single reply in this thread. Don't worry about it too much, sometimes you get a little hit but is normally tends upwards. Cheers, R. Pereant, qui ante nos nostra dixerunt!	[reply]
Re^5: regex: extract multiple number of date patterns from certain lines by Marshall (Canon) on Mar 06, 2009 at 20:34 UTC
Hi, I am trying to be helpful, not just argumentative just for the sake of arguing. I looked at this: http://search.cpan.org/~rcaputo/POE-1.003/lib/POE/Wheel/FollowTail.pm#Filter I have no experience at all with this module. But it looks like you can call a sub when a new line appears and that sub can do what it wants with that line. Maybe my impression is wrong somehow..That's always possible!. I do have some experience with regex (and I'm not a regex guru by any means!). But my experience with this is that 2 regex's that don't backtrack, don't use fancy look forward features, will run faster than a single fancy regex. There are also differences between say Perl 5.6 and Perl 5.10 regex engines! Perl 5.10 is much faster if that matters to you or you can take advantage of that. Your problem: date1 garbage qualifying_text date2,date3,date4... fits very nicely into the algorithm of skip the lines that don't have the qualifying_text and use match global for the dates on the lines that do have the qualifying_text.	[reply]