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

Lets say that you use Config::General for you config-file and that it contains these lines:

    extensions    avi flv mp3 mp4 wmv
    unwanted      frames svn

You could then use it like so (see the Config::General for more):

my $conf = Config::General->new('/path/to/myapp.conf')->getall();
my $extension_string = $conf{'MyApp'}{'extensions'};

my @extensions = split m{ }, $extension_string;

# Some sanity checks maybe...

my $regex_builder = join '|', @extensions;

$regex_builder = '.(' . $regex_builder . ')$';

my $regex = qr/$regex_builder/;

if($file =~ m{$regex}) {
    # Do something.
}


my $uw_regex_builder = '.(' . join ('|', split (m{ }, $conf{'MyApp'}{'unwanted'})) . ')$';
my $unwanted_regex = qr/$uw_regex_builder/;

if(File::Next::dir !~ m{$unwanted_regex}) {
    # Do something. (Note that this does not enforce /^.svn$/. You
    # will need some kind of agreed syntax in your conf-file for that.
}

(This is completely untested.)