[duplicate] PHP: Using a class function as a callback

Problem

I have a class that contains methods that I’d like to use as callbacks. How may they be used as arguments?

Class MyClass {

    public function myMethod() {
        $this->processSomething(this->myCallback); // How it must be called ?
        $this->processSomething(self::myStaticCallback); // How it must be called ?
    }

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

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

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

}

UPDATE: How to perform the same thing with a static method (in the case where $this isn’t available)

Asked by SmxCde

Solution #1

To learn about all the many ways to pass a function as a callback, consult the callable manual. I’ve copied that guidebook into this document and given some examples of each option based on your situation.

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

  // 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']);

  // 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+

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

Answered by MikO

Solution #2

There is a more elegant method to write it since 5.3, and I’m currently trying to figure out if it can be cut even further.

$this->processSomething(function() {
    $this->myCallback();
});

Answered by Bankzilla

Solution #3

You may also define a callback with call user func():

public function myMethod() {

    call_user_func(array($this, 'myCallback'));
}

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

Answered by Geovani Santos

Post is based on https://stackoverflow.com/questions/28954168/php-how-to-use-a-class-function-as-a-callback