Is it allowed to call non-static methods with call_user_func?

Question

When I use call_user_func on a non-static method in PHP 5.2 I get a Strict Warning:

Strict Standards: Non-static method User::register() cannot be called statically

But on PHP 5.3.1 I don't get this warning. Is this a bug in PHP 5.3.1 or is the warning removed?

Answer 1

It is perfectly OK -- but note that you have to pass an object that's an instance of your class, to indicate on which object the non-static method shall be called :

class MyClass {
    public function hello() {
        echo "Hello, World!";
    }
}

$a = new MyClass();
call_user_func(array($a, 'hello'));

You should not use something like this :

call_user_func('MyClass::hello');

Which will give you the following warning :

Strict standards: `call_user_func()` expects parameter 1 to be a valid callback,
non-static method `MyClass::hello()` should not be called statically 

(This would work perfectly fine if the method was declared as static... but it's not, here)

For more informations, you can take a look at the callback section of the manual, which states, amongst other things (quoting) :

A method of an instantiated object is passed as an array containing an object at index 0 and the method name at index 1.

If you get a strict error with an old version of PHP (e.g. 5.2), it's probably a matter of configuration -- I'm thinking about the error_reporting directive.

Note that E_ALL includes E_STRICT from PHP 5.4.0 (quoting) :