How can I add relative paths to libraries in perl? - perl

Question

I want to have a library (my_library_1) which makes use of another library in a folder relative to itself. If I write it like this:
use lib "/./libraries/";
use my_library_2;
It will use the path from where I execute the script.
If I use the following as proposed in other similar quiestions:
use FindBin;
use lib "$FindBin::Bin/./libraries/";
use my_library_2;
It will be relative to the main script being executed, therefore if I'm calling this library from another script, and then this library calles the other one (my_library_1), the library declaration will not be as expected if the first library (my_library_1) and the main script are in the same folder.
How can I solve this issue without relying on absolute paths?
Edit: To add some more information
This is the current structure:
folder
\_folder_1
\__main_script
\_folder_2
\__my_library_1
\__folder_1
\___my_library_2
I want to reference library_3 from library_2 with a relative path. The two proposed options do not work when I use them on "my_library_2".

Answer 1

lib::relative is a straightforward way to use __FILE__ to add absolutized lib paths relative to either a script or module. It also documents the equivalent core module commands so it doesn't need to be installed.
In the script:
use lib::relative '../folder2';
or:
use Cwd ();
use File::Basename ();
use File::Spec ();
use lib File::Spec->catdir(File::Basename::dirname(Cwd::abs_path __FILE__), '../folder2');
Similarly in the module:
use lib::relative 'folder1';
I recommend the much simpler __FILE__ approach over FindBin in all cases - FindBin is action at a distance, requires workarounds, and has serious bugs on old Perls that cannot be fixed because it isn't available on CPAN.

Answer 2

Here is one approach using __FILE__ to get the directory name of my_library_1.pm:
folder1/main.pl:
use strict;
use warnings;
use FindBin;
use lib "$FindBin::RealBin/../folder2/";
use my_library_1;
folder2/my_library_1.pm:
package my_library_1;
use strict;
use warnings;
use File::Basename qw(dirname);
my $dir;
BEGIN {
$dir = dirname(__FILE__);
}
use lib "$dir/folder1";
use my_library_2;