Namespaces are a great gift, and I'd recommend to using them :) Why don't you just place your standard library in an includable module (I usually name them MyProject::Utils or such) and use Exporter's functionality to import the wanted subroutines into the requesting namespace?(1)

Like choedebeck pointed out, require will load the file only once. You might want to use 'do' for a quick solution, tho I'd recommend the Exporter version.

1. (untested, see perldoc Exporter for more)

package MyProject::Utils;
use warnings;
use strict;
use base qw/ Exporter /;
use vars qw/ @EXPORT_OK /;
@EXPORT_OK = qw/ mysub_foo mysub_bar /;
sub mysub_foo { ... }
sub mysub_bar { ... }
...

use MyProject::Utils qw/ mysub_bar /;
my $x = mysub_bar( 23 );
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