Thank you for jogging my memory: 
use strict;

my $sub = sub {
    print "Hello!\n";
};

my $var = 'Bar';
my $pak = 'Foo::';
my $ref = \%main::;

$ref->{'Foo::'}{bar} = $sub;
$main::{'Foo::'}{$var} = $sub;
$ref->{$pak}{baz} = $sub;
$main::{$pak}{boo} = $sub;

Foo::bar();
Foo::Bar();
Foo::baz();
Foo::boo()

[download]
Update: added variable package name examples

In reply to Re: Re: Defining a subroutine in another package by chromatic
in thread Defining a subroutine in another package by jmay

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