Late Static Binding in PHP

LateStaticBinding.php

class Foo {
    public static $attr = 'foo';

    public static function getAttr() {
        return static::$attr;
    }
    public static function getAttr2() {
        return self::$attr;
    }
}

class Bar extends Foo {
    public static $attr = 'bar';

    public static function getAttr3() {
        return static::$attr;
    }

    public static function getAttr4() {
        return self::$attr;
    }
}

echo Foo::getAttr(); // 'foo'                                                                                        
echo Bar::getAttr(); // 'bar'                                                                                        

echo Foo::getAttr2(); // 'foo'                                                                                       
echo Bar::getAttr2(); // 'foo'                                                                                       

echo Bar::getAttr3(); // 'bar'                                                                                       
echo Bar::getAttr4(); // 'bar'