In this example we are not able to call

who()

method of the child class

B

from parent class

A

class A {
    public static function who() {
        echo __CLASS__;
    }
    public static function test() {
        self::who();
    }
}

class B extends A {
    public static function who() {
        echo __CLASS__;
    }
}

B::test();

The code will call

who()

method of parent class and print its name

A

If we need

test()

to call

who()

method of child class

B

from parent class, then we can use

late static binding

technique. To achieve it, we use

static

keyword:

class A {
    public static function who() {
        echo __CLASS__;
    }
    public static function test() {
        static::who(); // Here comes Late Static Bindings
    }
}

class B extends A {
    public static function who() {
        echo __CLASS__;
    }
}

B::test();