php观察者模式入门例子

2. class DemoSubject implements SplSubject{
3. private $observers, $value;
5. public function __construct(){
6. $this->observers = array();
7. }
9. public function attach(SplObserver $observer){
10. $this->observers[] = $observer;
11. }
13. public function detach(SplObserver $observer){
14. if($idx = array_search($observer, $this->observers, true)){
15. unset($this->observers[$idx]);
16. }
17. }
19. public function notify(){
20. foreach($this->observers as $observer){
21. $observer->update($this);
22. }
23. }
25. public function setValue($value){
26. $this->value = $value;
27. $this->notify();
28. }
30. public function getValue(){
31. return $this->value;
32. }
33. }
35. class DemoObserver implements SplObserver{
36. public function update(SplSubject $subject){
37. echo 'The new value is '. $subject->getValue();
38. }
39. }
41. $subject = new DemoSubject();
42. $observer = new DemoObserver();
43. $subject->attach($observer);
44. $subject->setValue(5);

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