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Re^2: fastest pattern match

by flounder99 (Friar)
on Jun 24, 2002 at 19:50 UTC ( [id://176918]=note: print w/replies, xml ) Need Help??

in reply to Re: fastest pattern match
in thread fastest pattern match

You should use m/$regex/o or the regex will be compiled every iteration, slowing things down considerably



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Re: Re^2: fastest pattern match
by japhy (Canon) on Jun 24, 2002 at 22:29 UTC
    Incorrect. It will not be compiled on every iteration, but its string form will be compared with its previous string form, to see whether it needs recompiling.

    Jeff[japhy]Pinyan: Perl, regex, and perl hacker, who'd like a job (NYC-area)
    s++=END;++y(;-P)}y js++=;shajsj<++y(p-q)}?print:??;


      I remember reading that it still did the recompile even if the variable in the regex did not change. Of course I read that a LONG time ago. Apparently it has been fixed.(probably a long time ago) So would the /o faster by avoiding the extra string compare? I know this would probably be insignificant unless there where a bajillion iterations. But I was just curious.
      Do you even know anything about regexes? (see sig)



      Do you even know anything about perl?
      --Anonymous Coward to Tom Christiansen on slashdot

by frankus (Priest) on Jun 25, 2002 at 12:40 UTC

    That's JAN-AR-IK..(like generic) Just another Regexp Question.

    Also it might be worth mentioning that meta characters in $regex will still be parsed. Make sure you intended that to happen.


    Brother Frankus.


Re: Re^2: fastest pattern match
by d4vis (Chaplain) on Jun 24, 2002 at 20:11 UTC
    Good advice in general,
    but in this case there'll only be one interation.

    Update: Fastolfe's bad...mea culpa

    ~monk d4vis

      Why? If we were sure the match would always occur on the first line, why search for it at all?

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