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Re^3: Pimp My RegEx

by jhourcle (Prior)
on May 31, 2005 at 20:02 UTC ( #462197=note: print w/ replies, xml ) Need Help??


in reply to Re^2: Pimp My RegEx
in thread Pimp My RegEx

Sometimes, a comment will work just as well, without the overhead. Consider the following:

local $/; # INPUT_RECORD_SEPARATOR

As another option, in the documenation for 'English', there's a suggestion to use:

use English qw( -no_match_vars ) ;

to prevent the problems mentioned.

As for the 'evil variables', the following note is in 'perldoc perlre':

WARNING: Once Perl sees that you need one of $&, $`, or $' anywhere in the program, it has to provide them for every pattern match. This may substantially slow your program. Perl uses the same mechanism to produce $1, $2, etc, so you also pay a price for each pattern that contains capturing parentheses. (To avoid this cost while retaining the grouping behaviour, use the extended regular expression "(?: ... )" instead.) But if you never use $&, $` or $', then patterns without capturing parentheses will not be penalized. So avoid $&, $', and $` if you can, but if you can't (and some algorithms really appreciate them), once you've used them once, use them at will, because you've already paid the price. As of 5.005, $& is not so costly as the other two.


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Re^4: Pimp My RegEx
by heathen (Acolyte) on May 31, 2005 at 20:24 UTC

    Thanks for the advice jhourcle!
    I've got a few scripts out there I'm going to have apply the "-no_match_vars" to. I didn't realize "Use English" came with baggage.

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