====== Request for Comments: LSB, parent::/self:: forwarding ======
  * Version: 1.0
  * Date: 2008-07-22
  * Author: Etienne Kneuss <colder@php.net>
  * Status: Implemented in PHP 5.3

===== Introduction =====

This RFC covers the change that occured to Late Static Bindings (LSB) prior to its first alpha release.

==== Terms and concepts ====

LSB works by passing the original call info to the function, used then by ''static::'' or get_called_class to get the original class name used. This information will only be useful in case a ''fallback'' occurs, which takes place when you call a static method that only exists in one of the parent classes.
<code php>
<?php
  class A {
     public static function who() {
        return get_called_class();
     }
  }
  class B extends A {
     
  }
  class C extends B {

  } 
  echo C::who(); // C
?>
</code>

Now let's say that you want to overwrite who in B, but still rely on A's who():

<code php>
<?php
  class A {
     public static function who() {
        return get_called_class();
     }
  }
  class B extends A {
     public static function who() {
         /* do stuff.. */

         /* call A's who() */
     }  
  }
  class C extends B {

  } 
  echo C::who(); // ??
?>
</code>

Now, depending on how you call A's ''who()'' from ''B::who()'', you might get different results for the ''C::who()'' call:
  - C, if the call was ''forwarding''
  - A, if the call wasn't ''forwarding''.

===== The change =====

Previously, ''A::who()'' and ''parent::who()'' would be ''non-forwarding''. The only way to call A's who() with ''forwarding'' was to use an helper function: ''forward_static_call()''.

With the change, a difference between ''parent::'' and ''A::'' is introduced, that is: ''parent::'' is ''forwarding'' while ''A::'' isn't. Basically, explicit calls are ''non-forwarding'', but calls using keywords are.

Note that ''self::'' will also be made to be ''forwarding'', while ''<nameoftheclass>::'' won't.

===== ML Discussion =====

http://markmail.org/message/at3ypbykl6luwr6l