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We may not be so familiar with the observer pattern. It is an event system, which means that this pattern allows a class to observe the state of another class. When the state of the observed class changes, When, the observation class can receive notifications and take corresponding actions; the observer pattern provides another way to avoid tight coupling between components; so let’s discuss what the observer pattern is in this article!
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Observer:
It is an event system, which means that this pattern allows a class to observe the state of another class when When the state of the observed class changes, the observing class can receive notifications and take corresponding actions; the observer pattern provides another way to avoid tight coupling between components;
We still use code For example, we create a new file, then define a class, and then write a member attribute in the class, which is an array to store observers, and then we define a method, which is used to store observers and Adding an observer allows the observer to be notified and make a certain response when the observed behavior is performed. The code is as an example:
<?php class Man { //用来存放观察者 protected $observers = []; //添加观察者方法 function addObserver($observer) { $this->observers[]=$observer; } //花钱方法 function buy() { //当被观察者做出这个行为的时候,让观察者得到通并且做出一-定的反应 foreach ($this->observers as $girl) { $girl->pome(); } } } class GirlFriend { function pome() { echo'我只明白一件事,爱一个人,是那么痛苦<br />'; } } //创建对象 $xiaoming = new Man(); $xiaohua =new GirlFriend(); $xiaoli = new GirlFriend(); //添加观察者 $xiaoming->addObserver( $xiaohua); $xiaoming->addObserver($xiaoli); $xiaoming->buy();
The running results are as follows:
If there is a method to add an observer, then there is a method to delete an observer, so we also need to add a method to delete an observer,
function delObserver($observer) { //查找对应值在数组中的键 $key = array_search($observer,$this->observers); //根据键删除值,并且数组重新索引 array_splice($this->observers, $key, 1); } }
//Delete
$xiaoming->delObserver( $xiaohua);
The code is as follows:
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