How about making it all explicit, put $foo in its own package, and just be judicious in your use of the full name of $foo.

#!/usr/bin/perl -w

use strict;

package Foo;

use vars qw/$foo/;
$foo = "bar";

package main;

# always use $Foo::foo from here on down
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Or you could exploit the fact that my variables scope, while it stretches across packages declared in the same file, does not reach outside of the *file* in which they are declared. I.e. if in foo.pl you declare $foo with my, then that variable won't be visible inside subroutines declared in bar.pl

A little more souped-up kind of idea might be to define an *object* with accessor methods. Syntactically annoying (which I gather is what you're trying to avoid =), but IMO, conceptually quite clean.

final note: please, use a more descriptive title ... it might help others trying to solve the same problem =)

Philosophy can be made out of anything. Or less -- Jerry A. Fodor