PHP: “Call to undefined method” error when calling static method from parent

Question

How is the correct way to call a child class method from a parent class if both are static?

When I use static classes it returns the error " Call to undefined method A::multi() ", however when I use non-static methods there is no problem, for example:

//-------------- STATIC ------------------
class A {
    public static function calc($a,$b) {
        return self::multi($a, $b);
    }
}
class B extends A {
    public static function multi($a, $b) {
        return $a*$b;
    }
}
echo B::calc(3,4); //ERROR!!

//-------------- NON-STATIC ----------------
class C {
    public function calc($a,$b) {
        return $this->multi($a, $b);
    }
}
class D extends C {
    public function multi($a, $b) {
        return $a*$b;
    }
}
$D = new D();
echo $D->calc(3,4); // Returns: 12

Is there a way to call a child static method without knowing its class name?

Answer 1

It's only possible in PHP 5.3 and newer, with late static bindings , where PHP 5.3 is able to access static members in subclasses instead of whatever the class that self refers to because it's resolved during runtime instead of compile-time.

Unfortunately, I don't think there's a solution for this in PHP 5.2 and older.