PHP手册-call_user_func

// An example callback function
function my_callback_function() {
    echo 'hello world!';
}

// An example callback method
class MyClass {
    static function myCallbackMethod() {
        echo 'Hello World!';
    }
}

// Type 1: Simple callback
call_user_func('my_callback_function'); 

// Type 2: Static class method call 调用静态方法
call_user_func(array('MyClass', 'myCallbackMethod')); 

// Type 3: Object method call 调用实例的方法
$obj = new MyClass();
call_user_func(array($obj, 'myCallbackMethod'));

// Type 4: Static class method call (As of PHP 5.2.3) 调用静态方法
call_user_func('MyClass::myCallbackMethod');

// Type 5: Relative static class method call (As of PHP 5.3.0) 调用父类的静态方法
class A {
    public static function who() {
        echo "A\n";
    }
}

class B extends A {
    public static function who() {
        echo "B\n";
    }
}

call_user_func(array('B', 'parent::who')); // A