How to define a list of regular expressions?

pat_mc has asked for the wisdom of the Perl Monks concerning the following question:

Esteemed monks!

I have the following question for ye today: How can I define a list of regular expressions over which I subsequently want to iterate?

So far, I have tried the following, alas to no avail:

my @files = ( "File1", "File2", ... );

my @regexes = ( 'verb [\w<>]+\s+/', 'noun \w+\s+/', ... );

for my $file ( @files )
{
    my $regex = qr/shift @regexes/;

    ...

    $sizes{ $version }{ $file } ++ if /$regex/;
}
[download]

Syntax highlighting in my editor already informs me that this is syntactically unacceptable. I also tried various ways of quoting the entries in the list ... but none of them worked. The error message received is

Use of uninitialized value $regex in regexp compilation at ./compare.l
+exicons.pl line ...
[download]

Presumably, it is just a small thing I am overlooking -- but I simply cannot get it. Ideally, what I want is a list of compiled regular expressions that I can simply fetch using shift and interpolate where needed. Your help in this matter hence would be much appreciated.

Thanks a lot in advance and best regards -

Pat

Comment on How to define a list of regular expressions? Select or Download Code

Replies are listed 'Best First'.
Re: How to define a list of regular expressions? by Anonymous Monk on Jul 01, 2009 at 09:56 UTC
qr is quoting operator `my @regexes = ( qr'verb [\w<>]+\s+/', qr'noun \w+\s+/', ... ); for my $re (@regexes ){ $sizes{ $version }{ $file } ++ if /$re/; }` [download]	[reply] [d/l]
Re^2: How to define a list of regular expressions? by pat_mc (Pilgrim) on Jul 01, 2009 at 10:21 UTC
Thanks, Anonymous Monk ... What, though, if I do not want to loop over the regexes but retrieve them from the list via `shift` when needed? Can you point out to me where or why my code is broken? Thanks - Pat	[reply] [d/l]
Re^3: How to define a list of regular expressions? by grizzley (Chaplain) on Jul 01, 2009 at 12:09 UTC
Instead of `my $regex = qr/shift @regexes/;` do just `my $regex = shift @regexes;`	[reply] [d/l] [select]
Re: How to define a list of regular expressions? by JavaFan (Canon) on Jul 01, 2009 at 10:03 UTC
Syntax highlighting in my editor already informs me that this is syntactically unacceptable. I'm curious. I don't spot a syntax error in your code fragment (except for the '...' parts).	[reply]
Re^2: How to define a list of regular expressions? by pat_mc (Pilgrim) on Jul 01, 2009 at 10:18 UTC
Very observant of you, JavaFan - I misinterpreted my editor's change in highlighting colour inside the slashes which was due to the fact that the quote contained a variable, not a syntax error. Please ignore my comment on the syntax error.	[reply]
Re^2: How to define a list of regular expressions? by afoken (Chancellor) on Jul 01, 2009 at 14:36 UTC
I don't know a single editor that can properly syntax-highlight arbitary perl code. Some editors are rather clever, but some are already confused when the code contains POD. Quotes in regular expressions with slash-replacements confuse all editors I know. Alexander -- Today I will gladly share my knowledge and experience, for there are no sweeter words than "I told you so". ;-)	[reply]
Re^3: How to define a list of regular expressions? by Anonymous Monk on Jul 01, 2009 at 14:49 UTC
Quotes in regular expressions with slash-replacements confuse all editors I know. You must not know Scintilla based editors (scite/notepad++...) or jEdit :)	[reply]
Re: How to define a list of regular expressions? by AnomalousMonk (Archbishop) on Jul 01, 2009 at 13:08 UTC
And, to avoid looping through all the regexes, it's possible to combine the individual regexes into a single regex (probably a big performance win if there are many regexes): `>perl -wMstrict -le "my @regexes = ( qr{ foo }xms, qr{ bar }xms, qr{ baz }xms, ); my $any_regex = qr{ @{[ join '\|', @regexes ]} }xms; for my $file (@ARGV) { print $file, $file =~ $any_regex ? ' MATCHES' : ' no match'; } " xfooy snork bar xfooy MATCHES snork no match bar MATCHES` [download] Remember, however, that Perl's `\|` (vertical bar) regex alternation operator provides ordered alternation: the overall alternation will match with whatever sub-pattern first matches in the alternation sequence, regardless of length. See Matching this or that in perlretut.	[reply] [d/l] [select]
Re^2: How to define a list of regular expressions? by poolpi (Hermit) on Jul 02, 2009 at 07:32 UTC
See Regexp::Assemble `#!/usr/bin/perl use strict; use warnings; use Regexp::Assemble; my $ra = Regexp::Assemble->new->add(qw[foo bar baz]); print $ra->re, "\n"; for (qw[xfooy snork bar]) { print " $_ does " . ( /$ra/ ? '' : 'not ' ) . "match\n"; } __END__ Output: (?-xism:(?:ba[rz]\|foo)) xfooy does match snork does not match bar does match` [download] hth, PooLpi 'Ebry haffa hoe hab im tik a bush'. Jamaican proverb	[reply] [d/l]
Re: How to define a list of regular expressions? by rovf (Priest) on Jul 01, 2009 at 11:39 UTC
Use of uninitialized value $regex My guess: In your code you initially have `@files > @regexes`. -- Ronald Fischer <ynnor@mm.st>	[reply] [d/l] [select]