通过父函数的静态变量访问防止后期静态绑定

Question

Given the following class hierarchy:

class ParentClass {
    private static $_test;

    public function returnTest() {
        return static::$_test;
    }
}
class ChildClass extends ParentClass {
    // intentionally left blank
}
$child = new ChildClass();
echo $child->returnTest();

The output generated is the following error message:
Fatal error: Cannot access property ChildClass::$_test
Is there a way to prevent late static binding from happening? Since I am calling a function of a parent class that is not overwritten, I feel like I should be allowed to do something like the above.

Answer 1

You are calling a static property from an instantiated class. Just use the name of the class:

return static::$_test;

Answer 2

Use return self::$_test instead of return static::$_test .

This insures that you access the field $_test of the class where returnTest is defined.

See http://www.php.net/manual/en/language.oop5.late-static-bindings.php for reference.