execute (magic) method when existing method is called

Question

Is there a magic method that when a certain method is called from an object, that a magic method is called first. Kinda like the __call method, but this only gets triggered when the method isn't found.

So in my case i'd like something like this:

class MyClass
{
    public function __startMethod ( $method, $args )
    {
        // a method just got called, so  this is called first
        echo ' [start] ';
    }

    public function helloWorld ( )
    {
        echo ' [Hello] ';
    }
}

$obj = new MyClass();
$obj->helloWorld();

//Output:
[start] [Hello] 

Does something like this exist in PHP??

Answer 1

There isn't a direct way to do this but it looks to me like your trying to implement a form of Aspect Oriented programming. There are several ways of achieving this in PHP, one would be to set up your class something like the following:

class MyClass
{
    public function __startMethod ( $method, $args )
    {
        // a method just got called, so  this is called first
        echo ' [start] ';
    }

    public function _helloWorld ( )
    {
        echo ' [Hello] ';
    }

    public function __call($method, $args)
    {
        _startMethod($method, $args);
        $actualMethod = '_'.$method;
        call_user_func_array(array($this, $actualMethod), $args);
    }
}

$obj = new MyClass();
$obj->helloWorld();

Look up other ways of implementing AOP in PHP to see what works best for you (I'll see if I can find a link somewhere).

EDIT: here's a document for you http://www.liacs.nl/assets/Bachelorscripties/07-MFAPouw.pdf

Answer 2

No there is no magic method for this.

The best you could do is create other names for your functions (eg: hidden_helloWorld), then catch all the calls with __call and try to call the hidden_ method if it is available. Of course this is only possible if you have full control over the naming of the class and its parent, etc...

Answer 3

YOu could achieve it by making your methods private and calling the methods using the __call() magic method. Like:

<?php

class MyClass{
    function __call($methd, $args){
        if(method_exists($this, $mthd)){
            $this->$mthd($args);
        }
    }

    private function mthdRequired($args){
        //do something or return something
    }

The mthdRequired method doesnt get called except using call. I hope this is usefull.