If you unshift @INC, you have to do it in a BEGIN clause before using it.

Here's an example from my darkpan repo: If you normally install your module in @INC (for example as part of a CPAN distribution), but don't want the hassle while debugging, you can do something like this:

use strict;
use warnings;

BEGIN {
    if(defined($ARGV[0]) && $ARGV[0] eq "--debug") {
        print("Development INC activated\n\n");
        unshift @INC, "/home/cavac/src/maplat_prodit/lib"; # my darkpa
+n modules
        unshift @INC, "/home/cavac/src/maplat_framework/lib"; # my ope
+n source modules
    } else {
        print("Development INC deactivated, using default INC paths\n\
+n");
    }
}

use Maplat::Worker;
use Maplat::Worker::ProdIT;
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