#!/usr/bin/perl

package Env::Tie;

use strict;
use Tie::Hash;
our @ISA = qw/Tie::StdHash/;

sub TIEHASH { bless $_[1] , $_[0] }
sub FETCH { $_[0]->{$_[1]} . '---BWUBUBWU' }
# The '---BWUBUBWU' of course being 
# dynamic generated content

package Test;

use strict;
sub print { print 'env home =', $ENV{HOME}, "\n" }

package main;

use strict;

print "Hic sunt leones\n";
print 'env home =', $ENV{HOME}, "\n";
print "lets go\n";

my %self = %ENV;
tie %ENV, 'Env::Tie', \%self;

print "tied ENV\n";
print 'env home =', $ENV{HOME}, "\n";

print "lets try it in an other package\n";
Test::print();

print "lets fork perl\n";
system(
    'perl', 
    '-e', 
    q{print 'env home =', $ENV{HOME}, "\n"} 
);

print "lets fork bash\n";
system(
    'bash', 
    '-c', 
    q{echo $HOME}
);

print "done\n";