Three classes summarize the five design patterns of PHP_PHP Tutorial

class people {
private $name = '';
private $user = null;
private function __contract($name){/*Here private definition assists in implementing a single element Pattern*/
$this->name = $name;
}
public static function instance($name){/*This method implements the factory pattern*/
static $object = null; /*This variable implements single element mode*/
if (is_null($object))
$object = new people($name);
return $object;
}
public function work_in($who=null)
{
if (is_null($who)) echo 'error';
else {
$this->user[] = $who;/*this Array variables implement observer mode*/
echo $who->work();/*This method calls to implement strategy mode*/
}
}
public function on_action($which=' '){
if (empty($which)) echo 'error';
else {
foreach ($this->user as $user)
$user->action($ which);/*This method call implements the command chain mode*/
}
}
}
$people = people::instance('jack');
$people-> work_in(new student);
$people->work_in(new teacher);
$people->on_action('eat');
class student {
function work(){
echo '
I am a student, working 9 to 5. ';
}
function action($which){
if (method_exists($this, $which)) return $this->$which();
else echo 'you are wrong !';
}
function eat(){
echo '
I am a student and can only eat set meals. ';
}
}
class teacher {
function work(){
echo '
I am a teacher, and I am busiest preparing lessons at night. ';
}
function action($which){
if (method_exists($this, $which)) return $this->$which();
else echo 'i can not do it!';
}
function eat(){
echo '
I am a teacher and can eat big meals every day. ';
}
}