PHP 5.3 - Late Static Binding

late_static_binding.php

<?php

class Foo{
  protected static function speak(){
    echo __METHOD__, "\n\r";
    return 'Hi';
  }

  public static function sayHi(){
    //return self::speak(); // PHP 5.2 <=
    return static::speak(); //PHP 5.3
  }
}

class Bar extends Foo {
  protected static function speak(){
    echo __METHOD__, "\n\r";
    return 'Hello';
  }
}

/*
output: 
Bar::speak
Hello
*/
echo Bar::sayHi();