I'm not advocating this as the best method but since nobody else has brought it up I thought I should. You can re-open name spaces with the 'package' keyword. The best example of this (that I can think of) are the plugins for Mail::Audit.

from Mail/Audit/KillDups.pm

package Mail::Audit::KillDups;
use Mail::Audit;
use vars qw(@VERSION $dupfile $cache_bytes);
$VERSION = '1.9';
$dupfile = ".msgid-cache";
$cache_bytes = 10000;
1;

package Mail::Audit;
use strict;
use Fcntl;

sub killdups {
.
.
.
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