calluserfuncarray_with_key.php

<?php

class Test {

  protected $_data = array();

  public function __call($method, $args) {
    if (substr($method, 0, 3) == 'set') {
      $key = strtolower(substr($method, 3));
      if (isset($args[0])) {
        $this->_data[$key] = $args[0];
      }   
    }   
  }

  public function dump() {
    var_dump($this->_data);
  }

}

$test = new Test();

// (obviously) works
$test->setHello('world');

// also works
call_user_func_array(array($test, 'setThis'), array('is cool'));

// doesn't work
call_user_func_array(array($test, 'setFoo'), array('bur' => 'bar'));

$test->dump();