#!/usr/bin,/perl -w
$x = "MAIN";  # in default package, "main"
package Foo;
$x = 123;     # in package "Foo", so this is $Foo::x
package Bar;
$x = 456;     # in package "Bar", so this is $Bar::x

package main;  # back to normal
print "\$$x = '$x'\n";
print "\$main::$x = '$main::x'\n";
print "\$Foo::$x = '$Foo::x'\n";
print "\$Bar::$x = '$Bar::x'\n";