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Re^2: Testing for the presence of a hash key in a filename

by Ojosh!ro (Beadle)
on May 25, 2007 at 16:09 UTC ( #617527=note: print w/replies, xml ) Need Help??


in reply to Re: Testing for the presence of a hash key in a filename
in thread Testing for the presence of a hash key in a filename

It's basically what I'd do too. I'd just construct the regex myself I guess.
Something along the lines of:
my $match = '('.join( '|', sort keys %replace ).')'; and then use the value in $replace{$1}

if( exists $aeons{strange} ){ die $death unless ( $death%2 ) }

Replies are listed 'Best First'.
Re: Testing for the presence of a hash key in a filename
by benizi (Hermit) on May 27, 2007 at 18:23 UTC

    It appears from the problem description that the keys are all three characters, but just as a heads-up, you might want to add a reverse to that:

    my $match = '('.join('|', reverse sort keys %replace).')';

    The reverse ensures that the longest match is found even if some pattern is a prefix of another (which, in my experience, is generally the desired outcome). e.g.:

    #!/usr/bin/perl -l use strict; use warnings; my %replace = qw/pre 1 prefix 2/; my $norev = '('.join('|', sort keys %replace).')'; my $withrev = '('.join('|', reverse sort keys %replace).')'; while (<DATA>) { chomp; print "Line: $_"; print "norev <$1>" if /$norev/; print "w/rev <$1>" if /$withrev/; } __END__ This line contains prefix (which also matches 'pre')

    Should print:

    Line: This line contains prefix (which also matches 'pre') norev <pre> w/rev <prefix>

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