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Re: mysterious regexp syntax

by Tux (Monsignor)
on Feb 04, 2014 at 08:46 UTC ( #1073348=note: print w/ replies, xml ) Need Help??


in reply to mysterious regexp syntax

$ man perlop : : If "/" is the delimiter then the initial "m" is optiona +l. With the "m" you can use any pair of non-whitespace (ASCII) characters as delimiters. This is particularly useful +for matching path names that contain "/", to avoid LTS (lea +ning toothpick syndrome). If "?" is the delimiter, then a m +atch- only-once rule applies, described in "m?PATTERN?" below +. If "'" is the delimiter, no interpolation is performed on +the PATTERN. When using a character valid in an identifier +, whitespace is required after the "m". : : m?PATTERN?msixpodualgc ?PATTERN?msixpodualgc This is just like the "m/PATTERN/" search, except that +it matches only once between calls to the reset() operator +. This is a useful optimization when you want to see only the +first occurrence of something in each file of a set of files, + for instance. Only "m??" patterns local to the current pa +ckage are reset.

Enjoy, Have FUN! H.Merijn


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Re^2: mysterious regexp syntax
by grizzley (Chaplain) on Feb 04, 2014 at 10:29 UTC
    Ahhhh... So possibility to omit 'm' remains in case of '?' delimiter. That is what I've been missing.
    # perl -le '$_="abc"; print 1 if ?b?'
    Thanks for clarification!

      But note the following, from perl5140delta:

      ?PATTERN? (without the initial m) has been deprecated and now produces a warning. This is to allow future use of ? in new operators. The match-once functionality is still available as m?PATTERN?.

      So with v5.14.4, I get:

      22:39 >perl -le "$_ = qq[abc]; print 1 if ?b?;" Use of ?PATTERN? without explicit operator is deprecated at -e line 1. 1 22:39 >

      Hope that helps,

      Athanasius <°(((><contra mundum Iustus alius egestas vitae, eros Piratica,

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