Scope Resolution Operator (::)

The Scope Resolution Operator (also called Paamayim Nekudotayim) or in simpler terms, the double colon, is a token that allows access to static, constant, and overridden members or methods of a class.

When referencing these items from outside the class definition, use the name of the class.

Paamayim Nekudotayim would, at first, seem like a strange choice for naming a double-colon. However, while writing the Zend Engine 0.5 (which powers PHP 3), that’s what the Zend team decided to call it. It actually does mean double-colon – in Hebrew!

class MyClass {
const CONST_VALUE = 'A constant value';
}

echo MyClass::CONST_VALUE;
?>

Two special keywords self and parent are used to access members or methods from inside the class definition. Calling a parent’s method

class MyClass
{
protected function myFunc() {
echo "MyClass::myFunc()n";
}
}

class OtherClass extends MyClass
{
// Override parent's definition
public function myFunc()
{
// But still call the parent function
parent::myFunc();
echo "OtherClass::myFunc()n";
}
}

$class = new OtherClass();
$class->myFunc();
?>