PHP: Call a method on a returned class

I have a method which returns a class and want to 开发者_StackOverflow中文版call a method on it. Instead of

$theClass = $this->getClass();
$theClass->foo();

I would like to write

$this->getClass()->foo();

Is there a syntax for this as of PHP4?

This works:

$this->{$this->getClassName()}->foo();

But I would like to manipulate the class beforehand (I do this now in getClass()).

Nope, it won't work in PHP4, this feature has been bettered in PHP5. I wonder why are you still using PHP4 :)