Question

normally, (in subtype definition) I use

function enable() {
  parent::enable();
 }

 function disable() {
  parent::disable();
 }

and then I call $subtypeinstance->enable()

but can I also use something like

$subtypeinstance->parent::enable() 

or

(SupertypeName)$subtypeinstance->enable()

Answer 1

You can actually call Parent::enable() or parent::enable() (i.e. class name or parent keyword) as PHP makes no distinction between static and instance calls and passes an instance anyway.

class Foo {
    public $x;
    public function bar() {
        echo "Foo::bar(), x is " . $this->x . "\n";
    }
}

class FooChild extends Foo {
    public function bar() {
        echo "FooChild::bar(), x is " . $this->x . "\n";
        Foo::bar();
        parent::bar();
    }
}

$foo = new Foo();
$foo->x = 42;
$foo->bar();

$fooc = new FooChild();
$fooc->x = 43;    
$fooc->bar();

Output:

Foo::bar(), x is 42
FooChild::bar(), x is 43
Foo::bar(), x is 43
Foo::bar(), x is 43

The parent keyword reference explains this and gives the same example.