# XYZ.pm
package XYZ;
use strict;
use warnings;
require Exporter;
our @ISA=qw/Exporter/;
our @EXPORT_OK = qw/PI CONST/;

our $PI = 3.14;
use constant CONST => 10.10;

1;

##</code><code>##

# example.pl
use strict;
use warnings;
use lib '.'; 
require XYZ;
print "PI=".$XYZ::PI."\n";
print "CONST=".XYZ::CONST."\n"; 

##</code><code>##

Bareword "XYZ::CONST" not allowed while "strict subs" in use at example.pl line 13.
Execution of example.pl aborted due to compilation errors.

##</code><code>##

Name "XYZ::PI" used only once: possible typo at example.pl line 11.
PI=3.14