Its best to avoid global data and mixing namespaces. But, if you must share your variables like this use Perl's Exporter facility, rather than hand coding your own system.

I've included code that shows how to share a scalar, but an array or hash would work identically. I also didn't use strict, which all production code should do. Nothing I did here will fail under strictures.

Shared variable module

package SharedVariables;
use base Exporter;

# Default export
@EXPORT    = qw( $scalar1 $scalar2 @array1 );

# Possible to export these
@EXPORT_OK = qw( $scalar1 $scalar2 @array1 @array2 );

# Named groups to export
%EXPORT_TAGS = (
    scalars => [ qw( $scalar1 $scalar2 ) ],
    arrays  => [ qw( @array1 @array2 ) ],
);

1;
[download]

Recieving module: Foo

package Foo;

use SharedVariables;

sub Print {

    print "Foo Scalar1 $scalar1\n";

}

sub Set {

    $scalar1 = 'Foo';
    print "Set Foo\n";

}

1;
[download]

Recieving Module: Bar

package Bar;

use SharedVariables qw(:scalars);

sub Print {

    print "Bar Scalar1 $scalar1\n";

}

sub Set {

    $scalar1 = 'Bar';
    print "Set Bar\n";

}


1;
[download]

Main program

use SharedVariables qw(:DEFAULT);
use Foo;
use Bar;

$scalar1 = 'Initialized';

print "Main Scalar1 $scalar1\n";
Foo::Print;
Foo::Set;
Foo::Print;
Bar::Print;
Bar::Set;
Bar::Print;
$scalar1 = 'Main';
Foo::Print;
Bar::Print;

__END__
C:\temp> test.pl
Main Scalar1 Initialized
Foo Scalar1 Initialized
Set Foo
Foo Scalar1 Foo
Bar Scalar1 Foo
Set Bar
Bar Scalar1 Bar
Foo Scalar1 Main
Bar Scalar1 Main
[download]

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