If you still feel like being paranoid, you can move the directory back into the object, and create a trivial Factory class that generates objects configured to a preset value. It gives you the same level of convenience, and factors the work of configuring the module into an explicit class:

package Module;

sub new {
    return (bless {}, shift);
}

sub use_directory {
    my $O = shift;
    $O->{'directory'} = shift;
    return;
}

sub jabber {
    my $O = shift;
    return ("dir = $O->{'directory'}");
}


package Factory;

sub new {
    return (bless {}, shift);
}

sub use_directory {
    my $O = shift;
    $O->{'directory'} = shift;
    return;
}

sub mk_module {
    my $O = shift;
    my $M = new Module;
    $M->use_directory ($O->{'directory'});
    return ($M);
}


package main;

$f1 = new Factory;
$f1->use_directory ('/usr/local');

$f2 = new Factory;
$f2->use_directory ('/var/log');

for (1..10) {
    $f = (rand() < .5) ? $f1 : $f2;
    push @modules, $f->mk_module;
}

for $m (@modules) {
    print $m->jabber, "\n";
}
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