How to have conditional libraries with Perl? [duplicate] - perl

Question

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Perl - Include package from relative path, which includes another package from a relative path?
(4 answers)
Closed 8 years ago.
I have homemade #Perl libraries that I'm moving from machine to machine, and the paths are not the same from place to place. Specifically, on the old machines, they existed in /home/foo/lib/, while they're moving to /group/bar/apps/lib on the new machines, and I now want to have them in something like /home/me/dev/Tools/lib.
What we did was have multiple use lib lines. /home/foo isn't available on the new machine, and /group/bar isn't a directory on the old machine, so when it sees this --
use lib '/home/foo/lib/' ;
use lib '/group/bar/apps/lib' ;
use Tools::Foo ;
-- everything is fine.
The problem is, they link to each other, and I'd rather not have something in /home/me/dev/Tools/lib load a program from /group/bar/apps/lib, and when I move this stuff to production, I don't want to have anything pointing back to ~/me/dev. Preferrably, I would want to not have to modify the code when I move it into production, so that, when everything is deployed, diff /group/bar/apps/lib/Tools/Foo.pm /home/me/dev/Tools/lib/Tools/Foo.pm would be empty.
So, how do I set things for multiple conditional library locations?

Answer 1

Options:
Properly install the modules.
Place your modules relative to the script
use FindBin qw( $RealBin );
use lib "$RealBin/../lib"; # Or whatever.
Use environment variable PERL5LIB rather than use lib.
The statements could be placed in sitecustomize.pl (if support for sitecustomize.pl was enabled when perl was built).

Answer 2

Using the following pragma
package lib_first_of;
use lib ();
use strict;
use warnings;
use Carp;
sub import {
foreach my $path (#_) {
if (-d $path) {
lib->import($path);
return 1;
}
}
croak "$0: no suitable library path found";
}
1;
lets your main program have the form
#! /usr/bin/env perl
use strict;
use warnings;
use lib_first_of (
"/home/foo/lib",
"/group/bar/apps/lib",
);
use MyModule;
print "done.\n";
If neither path is present, the program fails with errors resembling
my-program: no suitable library path found at my-program line 7
BEGIN failed--compilation aborted at my-program line 9.