use vars qw($foo);
$foo = "bar";              # assign the value 'bar' to variable $foo (package global)
print "$foo\n";            # prints bar
print "${*foo{SCALAR}}\n"; # also prints bar! same variable
${*foo{SCALAR}} = 'quux';  # assign a different value
print "$foo\n";            # prints 'quux', value has beeen changed