# file one
use File2;

File2::setup();
main();

# or ::main() (this package) or main::main() very specific
# "default" package name for main script (the one requiring other files) is 'main'

# print var foo from package File2
print $File2::foo . "\n";

sub main {
    print "I am in the main subroutine.\n";
}


# file 2
package File2;
sub setup {
    print "Setting up.\n";
}

$::foo = 'bar';

# or define explicitely
$File2::foo = 'bar';


1;    # use'd files have to return true!