$this not propagating in user_call_func_array() in PHP 5.3.4

I'm attempting to create an object which can be extended by additional classes after instantiation. I seem to have found a problem with user_call_func_array (and this family of functions) not propagating the $this variable properly.

Please consider the following:

// Base class
class baseClass {
    public $some_value = 'foobar';

    public function callManually() {
        extensionClass::extendedMethod('hello')开发者_如何转开发;
    }

    public function callDynamically($class,$method) {
        call_user_func_array("$class::$method",array('hello'));
    }
}

// Extension class
class extensionClass {
    public function extendedMethod($local_value) {
        if(isset($this)) {
            echo '$this is set. Local value = '.$local_value.'. Base value = '.$this->some_value."\n";
        } else {
            echo '$this is not set. Boo!'."\n";
        }
    }
}

// Create the base object and call extended method
$base_class = new baseClass;
$base_class->callManually();
$base_class->callDynamically('extensionClass','extendedMethod');

Both callManually() and callDynamically() invoke extendedMethod() within the extension class. Therefore, one would expect the script to produce the following:

$this is set. Local value = hello. Base value = foobar
$this is set. Local value = hello. Base value = foobar

However, because user_call_func_array isn't propagating $this correctly, I'm getting the following in PHP 5.3.4 on Mac OS X:

$this is set. Local value = hello. Base value = foobar
$this is not set. Boo!

Can anyone shed some light on this or offer an alternative solution to my problem?

Thanks.

It is natural if $this is not set in second call

$this denotes the current object of class but in your case the class itself is calling the method hence $this is not set.

class::method(); //The class itself is calling the method hence $this will be unset

Object->method();//$this will be set in this case because object is calling the method