How do I build Perl regular expressions dynamically?

Question

I have a Perl script that traverses a directory hierarchy using File::Next::files. It will only return to the script files that end in \".avi\", \".flv\", \".mp3\", \".mp4\", a

Answer 1

Its reasonably straight forward with File::Find::Rule, just a case of creating the list before hand.

use strict;
use warnings;
use aliased 'File::Find::Rule';


# name can do both styles. 
my @ignoredDirs = (qr/^.svn/,  '*.frames' );
my @wantExt = qw( *.avi *.flv *.mp3 );

my $finder = Rule->or( 
    Rule->new->directory->name(@ignoredDirs)->prune->discard, 
    Rule->new->file->name(@wantExt)
);

$finder->start('./');

while( my $file = $finder->match() ){
    # Matching file.
}

Then its just a case of populating those arrays. ( Note: above code also untested, but will likely work ). I'd generally use YAML for this, it makes life easier.

use strict;
use warnings;
use aliased 'File::Find::Rule';
use YAML::XS;

my $config = YAML::XS::Load(<<'EOF');
---
ignoredir:
- !!perl/regexp (?-xism:^.svn)
- '*.frames'
want:
- '*.avi'
- '*.flv'
- '*.mp3'
EOF

my $finder = Rule->or( 
    Rule->new->directory->name(@{ $config->{ignoredir} })->prune->discard, 
    Rule->new->file->name(@{ $config->{want} })
);

$finder->start('./');

while( my $file = $finder->match() ){
    # Matching file.
}

Note Using the handy module 'aliased.pm' which imports "File::Find::Rule" for me as "Rule".

• File::Find::Rule - Alternative interface to File::Find
• YAML::XS - Perl YAML Serialization using XS and libyaml
• aliased - Use shorter versions of class names.