Static creator with variable number of arguments

Question

I am looking for the best way to have a static creation method at the abstract level in a class family that can have a variable number of arguments in the constructor.

For example, if I know that all extended versions of Foo will have two constructor arguments, I could do this:

abstract class Foo {
    abstract public function __construct($arg1,$arg2);
    public static function Create(){
        $args = func_get_args();
        if(count($agrs)!=2) throw new Exception('Invalid number of arguments');
        $classname = __CLASS__;
        return new $classname($args[0],$args[1]);
    }
}

But how about the case where the constructor is not defined and the number of argumunts can vary:

abstract class Foo {
    public static function Create(){
        $args = func_get_args();
        $classname = __CLASS__;
        return new $classname($args[0],$args[1],$args[2]); //errors if less than 3 arguments were passed
    }
}

class Foo_1 extends Foo {
  public function __construct($arg1){
      //some code...
  }
}

class Foo_2 extends Foo {
  public function __construct($arg1,$arg2,$arg3){
      //some code...
  }
}

The best I could come up with is to test arguments passed like this:

public static function Create(){
    $args = func_get_args();
    $classname = __CLASS__;
    switch count($args){
        case 0: return new $classname();
        case 1: return new $classname($args[0]);
        case 2: return new $classname($args[0],$args[1]);
        //etc....
    }
}

Answer 1

The easiest way to do this is to use the Reflection system.

$reflector = new ReflectionClass($className);
$args = array('foo', 'bar');
// $instance will be an instance of $className
// $args should be an array containing the arguments to
// pass to the constructor
$instance = $reflector->newInstanceArgs($args);