php create class method at runtime

Question

I am wondering if there is a way to attach a new method to a class at runtime, in php. I mean, not on an instance level but directly to the class, so that all newly created instances, have this new method. Can such a thing be done with reflection?

Thanks

Answer 1

Yes, you can.

Below is the way to create method in runtime in php 5.4.x.

The anonymous function is represented by Closure class started from 5.3.x. From 5.4.x, it add a Closure::bind static method to bind the anonymous function to a particular object or class.

Example:

class Foo {      private $methods = array();       public function addBar() {        $barFunc = function () {          var_dump($this->methods);        };        $this->methods['bar'] = \Closure::bind($barFunc, $this, get_class());      }       function __call($method, $args) {           if(is_callable($this->methods[$method]))           {             return call_user_func_array($this->methods[$method], $args);           }      }  }   $foo = new Foo;  $foo->addBar();  $foo->bar(); 

Answer 2

Did some playing around with whole thing. Seems that only thing you can potentially do with ReflectionClass is to replace an existing method. But even that would be indirectly.

I actually do not know any class-based language, where dynamic classes exist (then again, my knowledge is quite limited). I have seen it done only in prototype-based languages (javascript, ruby, smalltalk). Instead what you can do, in PHP 5.4, is to use Closure and add new methods to an existing object.

Here is a class which would let you perform such perversion to any object:

class Container {     protected $target;     protected $className;     protected $methods = [];      public function __construct( $target )     {         $this->target = $target;     }      public function attach( $name, $method )     {         if ( !$this->className )         {             $this->className = get_class( $this->target );         }         $binded = Closure::bind( $method, $this->target, $this->className );         $this->methods[$name] = $binded;     }      public function __call( $name, $arguments )     {         if ( array_key_exists( $name, $this->methods ) )         {             return call_user_func_array( $this->methods[$name] , $arguments );         }          if ( method_exists( $this->target, $name ) )         {             return call_user_func_array(                  array( $this->target, $name ),                 $arguments                 );         }     }    } 

To use this, you have to provide constructor with an existing object. Here is small example of usage:

class Foo {     private $bar = 'payload'; }; $foobar = new Foo; // you initial object   $instance = new Container( $foobar ); $func = function ( $param ) {     return 'Get ' . $this->bar . ' and ' . $param; }; $instance->attach('test', $func); // setting up the whole thing   echo $instance->test('lorem ipsum'); // 'Get payload and lorem ipsum' 

Not exactly what you want, but AFAIK this is as close you can get.