Access to protected base class members of a subclass via another subclass.

gistfile1.php

<?php

class Base{
  protected $x;

  public function getX(){
    return $this->x;}}

/**
* This class tries to ensure that $x is always an integer.
*/
class GoodChild extends Base{
  public function setX($x){
    if (is_integer($x)){
      $this->x=$x;}}}

/**
* This class circumvents GoodChild's security system.
*/
class EvilChild extends Base{
  public function setX(Base $b, $x){
    $b->x=$x;}}

$good=new GoodChild();
$evil=new EvilChild();
$evil->setX($good, 'foo'); // Works!

Of course it works. Why wouldn't it? You're not going through GoodChild::setX().
Try https://gist.github.com/999471 instead.

I see you got the point of this gist. :-) It's a case against 'protected'.