php - 如何从一个类中获取常量，排除所有可能从 parent 那里继承下来的常量？

Question

在第二个示例中，PDO 正在用它的常量填充 MyClass，如何过滤掉它们？

class MyClass {
  const PARAM_1 = 1;
  const PARAM_2 = 2;
  const PARAM_3 = 4;

  function MyMethod() {
    $reflector = new ReflectionClass(__CLASS__);
    print_r($reflector->getConstants());
  }

}

$myInstance = new MyClass();
$myInstance->MyMethod();

//returns:
//Array
//(
//    [PARAM_1] => 1
//    [PARAM_2] => 2
//    [PARAM_3] => 4
//)

class MyClassPDO extends PDO {
  const PARAM_1 = 1;
  const PARAM_2 = 2;
  const PARAM_3 = 4;

  function MyMethod() {
    $reflector = new ReflectionClass(__CLASS__);
    print_r($reflector->getConstants());
  }

}

$myInstancePDO = new MyClassPDO('sqlite::memory:');
$myInstancePDO->MyMethod();

//Array
//(
//    [PARAM_1] => 1
//    [PARAM_2] => 2
//    [PARAM_3] => 4
//    [PARAM_BOOL] => 5
//    [PARAM_NULL] => 0
//    [PARAM_INT] => 1
//    [PARAM_STR] => 2
//    [PARAM_LOB] => 3
//    [PARAM_STMT] => 4
//    [PARAM_INPUT_OUTPUT] => -2147483648
//    [PARAM_EVT_ALLOC] => 0
//    [PARAM_EVT_FREE] => 1
//    [PARAM_EVT_EXEC_PRE] => 2
//....and so on

Answer 1

据我所知

function MyMethod() {
  $reflector = new ReflectionClass(__CLASS__);
  print_r(array_diff($reflector->getConstants(),$reflector->getParentClass()->getConstants()));
}