<?php

class mA
{
  const TEST = 'mA';

  public function getSelf()
  {
    return self::TEST;
  }

  public function getThis()
  {
    return $this::TEST;
  }
}

class mB extends mA
{
  const TEST = 'mB';
}

$t = new mB();

echo "getSelf : " . $t->getSelf()."\n";
echo "getThis : " . $t->getThis()."\n";