Question

I have a CGI interface that calls a Perl plugin. Those scripts are located in different folders and the Perl one is supposed to read an XML file that is located in another folder. To make it simple I give you an example:

/a/b/cgi-bin/test.cgi # calls test.pl
/e/plugins/test.pl # reads config.xml
/e/etc/config.xml

Now I don’t know how to make the Perl plugin to read the config file. Ofcourse I can’t write the path on the script because tomorrow I may change the location of this file. I tryed using Cwd and abs_path on test.pl but this method returns the “running” path when instead I want the “location” path of test.pl so I can modify it in order to build the config.xml path. Any ideas?

EDIT: Using realpath instead of abspath solved my problem, or at least it seems so, I’ll do more tests.

EDIT2: Ok realpath works but now I have another problem… The Perl plugin uses some additional packages that I made but ofcourse now writing use MyPackage; doesn’t work anymore because it looks on the wrong folder… Is there a way to modify the environment variable? I don’t know something that will avoid me from changing thousands lines of code.

EDIT3: Ok solved that too somehow, I guess I will just install my packages in the INC folder so I don’t have to mess up with my code anymore.

Answer 1

The following function will return the path of an used()ed package:

use Cwd qw/abs_path/; 

sub get_module_folder {
  my $mkey = shift;
  $mkey =~ s|\:\:|/|g;
  $mkey .= '.pm';
  my $mpath = $INC{$mkey};
  $mpath =~ s|/[^/]+$||;
  return abs_path($mpath);
}

So if test.pl implements a package, say Plugin::Foo, then just call it as:

use Plugin::Foo;
open my $f, '<', get_module_folder('Plugin::Foo').'/../etc/config.xml'
  or die "can't open config file for reading: $!";

(Assuming that I’ve understood your folder structure correctly).

Updated: to use abs_path.

I often include this method in my own modules (replacing shift with __PACKAGE__) so that they can find any config/data they require.