PHP forward_static_call vs call_user_func

Question

What is the difference between forward_static_call and call_user_func

And the same question applies to forward_static_call_array and call_user_func_array

Answer 1

The difference is just that forward_static_call does not reset the "called class" information if going up the class hierarchy and explicitly naming a class, whereas call_user_func resets the information in those circumstances (but still does not reset it if using parent, static or self).

Example:

<?php
class A {
    static function bar() { echo get_called_class(), "\n"; }
}
class B extends A {
    static function foo() {
        parent::bar(); //forwards static info, 'B'
        call_user_func('parent::bar'); //forwarding, 'B'
        call_user_func('static::bar'); //forwarding, 'B'
        call_user_func('A::bar'); //non-forwarding, 'A'
        forward_static_call('parent::bar'); //forwarding, 'B'
        forward_static_call('A::bar'); //forwarding, 'B'
    }
}
B::foo();

Note that forward_static_call refuses to forward if going down the class hierarchy:

<?php
class A {
    static function foo() {
        forward_static_call('B::bar'); //non-forwarding, 'B'
    }
}
class B extends A {
    static function bar() { echo get_called_class(), "\n"; }
}
A::foo();

Finally, note that forward_static_call can only be called from within a class method.