package Stasher; 

sub stash {
    my $ns = caller;
    $ns    = $ns . '::';
    ${ $Stasher::{$ns}{foo} } = 'cheese';
};

##</code><code>##

package Stasher; 
our %stash_of;

sub stash {
    my $ns = caller;
    $stash_of{$ns}{foo} = 'cheese';
};