use strict;
use var qw($readMode $writeMode $appendMode);

$readMode   = '';
$writeMode  = '>';
$appendmode = '>>';

sub openFile
{
my $mode = pop(@_)
open(FILENAME, $mode, EXPR);
}

##</code><code>##

use strict;

require "moduleA.pl";
openFile("someOtherStuff", $readMode);