Passing regex to a subroutine

ll001 has asked for the wisdom of the Perl Monks concerning the following question:

Happy Friday Monks! I was wondering how I would pass a regex like this:

(/opt/backups/maindb[0-9]+.db/table[0-9]+.tn/chunk[0-9]+.cn/)
[download]

as an argument to a subroutine which executes a command on the (one and only) path matching that regex? Sample below hopefully illustrates what I'm trying to do.

#!/usr/bin/perl -w
use strict;

my $regexStr = qr{[0-9]+};
my $suff = ".dn";

listThisFolder($regexStr);

sub listThisFolder
{

    my ($regexStr) = @_;
        my $getDir = ("c:\\sh\\");
    
    # I know that the folder exists, but I don't know what the table
        # suffix or chunk suffix would be (table-129.tn or table-001.t
+n, etc).
    # $ls would hold the contents of the folder which expanded from th
+e regex
    
    my $ls = `dir $getDir$regexStr$suff`;
        print "$ls\n";
    #return($ls);
}
[download]

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Re: Passing regex to a subroutine by aitap (Curate) on Oct 12, 2012 at 19:33 UTC
Did you mean `my @list = grep { $_ =~ $regexStr } glob "$getDir/*";`? _(untested) Sorry if my advice was wrong.	[reply] [d/l]
Re^2: Passing regex to a subroutine by ll001 (Initiate) on Oct 12, 2012 at 19:47 UTC
That's what was missing. I had created a chicken and egg situation for myself because I had not expanded it correctly. Thanks for the help. -J	[reply]
Re^3: Passing regex to a subroutine by mbethke (Hermit) on Oct 12, 2012 at 21:26 UTC
Actually your problem was that you passed the regex to a command (`dir`) that didn't understand it. Doing it all in Perl makes much more sense of course, but if the suffix is significant you'll still have to integrate it into the regex.	[reply]
Re: Passing regex to a subroutine by Lotus1 (Vicar) on Oct 12, 2012 at 23:13 UTC
This is not exactly what you asked for but another option is to use File::Find. #!perl; use warnings; use strict; use File::Find; my $path = 'c:\b\perlmonks\arrays'; my $regexStr = qr{([0-9])\1[0-9]([0-9])\2}; my @files; find( sub { !-d and /$regexStr/ and print "<$_>\n" and push @files, $F +ile::Find::name }, $path ); print "1- $_\n" foreach glob("$path\\"); print "2- $_\n" foreach @files; __END__ Output: <997882.pl> <997882.txt> 1- c:\b\perlmonks\arrays\964788.pl 1- c:\b\perlmonks\arrays\966409.pl 1- c:\b\perlmonks\arrays\970295.pl 1- c:\b\perlmonks\arrays\997235.pl 1- c:\b\perlmonks\arrays\997829.pl 1- c:\b\perlmonks\arrays\997882.pl 1- c:\b\perlmonks\arrays\997882.txt 1- c:\b\perlmonks\arrays\fff2.txt 1- c:\b\perlmonks\arrays\junk 2- c:\b\perlmonks\arrays/997882.pl 2- c:\b\perlmonks\arrays/997882.txt [download]	[reply] [d/l]
Re: Passing regex to a subroutine by AnomalousMonk (Archbishop) on Oct 13, 2012 at 10:33 UTC
Another debugging approach is to ask what all those strings look like when they're concatenated together inside the function. `>perl -wMstrict -le "my $regexStr = qr{[0-9]+}; my $suff = '.dn'; my $getDir = 'c:\sh\\'; ;; my $concat = qq{$getDir$regexStr$suff}; print qq{for debug: '$concat'}; " for debug: 'c:\sh\(?^:[0-9]+).dn'` [download] The first thing that catches the eye is that `(?^:[0-9]+)` stuff in the middle of everything. What's that about? Clearly, it derives from the regex, but how does it relate to the specification of a path and file name? (Of course, one quickly realizes it is the stringization of the `Regexp` regex object – not a string at all – that `qr//` produces.) Seeing the inappropriate nature of the data being fed to the Windoze `dir` command is the first step toward thinking more clearly about what one ought to be doing.	[reply] [d/l] [select]
Re: Passing regex to a subroutine by kcott (Archbishop) on Oct 13, 2012 at 10:43 UTC
G'day ll001, I see that ++aitap has identified your problem. Seeing your usage of `$regexStr`, I was wondering if you were aware that `qr{...}` does not return a string per se. It actually returns a `Regexp` object. When stringified, this is overloaded to produce something you may not have expected. `$ perl -e 'my $regexStr = qr{[0-9]+}; print "$regexStr\n"; print ref($regexStr), "\n"; ' (?^:[0-9]+) Regexp` [download] See perlop - Regexp Quote-Like Operators for details. -- Ken	[reply] [d/l] [select]