Php 如何使用类方法作为回调

发布于03月10日

I have a class with methods that I want to use as callbacks.
How can I pass them as arguments?

Class MyClass {
    
    public function myMethod() {
        // How should these be called?
        $this->processSomething(this->myCallback);
        $this->processSomething(self::myStaticCallback);
    }

    private function processSomething(callable $callback) {
        // Process something...
        $callback();
    }

    private function myCallback() {
        // Do something...
    }

    private static function myStaticCallback() {
        // Do something...
    }   
    
}

推荐答案

查看callable manual以查看将函数作为回调传递的所有不同方式.我在这里复制了该手册，并根据您的场景添加了每种方法的一些示例.

可呼叫

PHP function以字符串的形式传递其名称.除了array()、echo、empty()、eval()、exit()、isset()、list()、print或unset()等语言构造之外，可以使用任何内置或用户定义的函数.

  // Not applicable in your scenario
  $this->processSomething('some_global_php_function');

method of an instantiated object作为数组传递，该数组包含索引0处的对象和索引1处的方法名.

  // Only from inside the same class
  $this->processSomething([$this, 'myCallback']);
  $this->processSomething([$this, 'myStaticCallback']);
  // From either inside or outside the same class
  $myObject->processSomething([new MyClass(), 'myCallback']);
  $myObject->processSomething([new MyClass(), 'myStaticCallback']);

Static class methods也可以通过传递类名而不是索引0处的对象来传递，而无需实例化该类的对象.

  // Only from inside the same class
  $this->processSomething([__CLASS__, 'myStaticCallback']);
  // From either inside or outside the same class
  $myObject->processSomething(['\Namespace\MyClass', 'myStaticCallback']);
  $myObject->processSomething(['\Namespace\MyClass::myStaticCallback']); // PHP 5.2.3+
  $myObject->processSomething([MyClass::class, 'myStaticCallback']); // PHP 5.5.0+

除了常见的用户定义函数外，anonymous functions还可以传递给回调参数.

  // Not applicable in your scenario unless you modify the structure
  $this->processSomething(function() {
      // process something directly here...
  });