php self parent 使用

<?phpclass Foo{ public static $my_static = '静1'; public function staticValue() { return self::$my_static; }}class Bar extends Foo{public static $my_static = '静2'; public function fooStatic() { return parent::$my_static; }}print Foo::$my_static . "<br />";//1$foo = new Foo();print $foo->staticValue() . "<br />";//2//print $foo->my_static . "<br />"; // Undefined "Property" my_static print $foo::$my_static . "<br />";//3$classname = 'Foo';print $classname::$my_static . "<br />"; // PHP 5.3.0之后可以动态调用3print Bar::$my_static . "<br />";//4$bar = new Bar();print $bar->fooStatic() . "<br />";//5?>