Description:
------------
Seems that there's no way to address the class constant from within a static method declared in the same class. Script is parsed by the engine, but I get a warning notice: Use of undefined constant 'xxx', assuming 'xxx'. The name of the constant assumed is identical to the one I want to address.

The substitution then occurs correctly, and script works. However, I couldn't find a way to call cosntant correctly to avoid warning message and guesswork from the engine.

self:: resolution operator doesn't help either.

Reproduce code:
---------------
include_once("db/PostGreSqlDbProfile.php");
include_once("db/MySqlDbProfile.php");
	
class InitStingray {
// constants
const PostgresDb = 'PostGreSQL';
const MysqlDb = 'MySQL';
	
// private variables
private static $currentDb = PostgresDb;
private static $db = NULL;		
		
// public methods
private static function initDb () {
  // xxx: problem addressing constant PostgresDb
  if (self::$currentDb == self::PostgresDb) {
    self::$db = new PostGreSqlDbProfile();
  }
  // xxx: problem addressing constant MySqlDb
  else if (self::$currentDb = self::MysqlDb) {
	self::$db = new MySqlDbProfile();
  }
}
		
public static function getDb () {
  if (self::$db == NULL) {
    self::initDb();
    return self::$db;	
  }
  else {
    return self::$db;
  }
}

}

Expected result:
----------------
Substitution of the name of the constant for its value should occur, and comparisons between variable $currentDb and predefined values "Postgres" and "Mysql" should take place. No warnings should be issued.

Actual result:
--------------
Warning is issued that the script cannot locate the constant I'm addressing, however guesses that I'm trying to call a cosntant with the same name and correctly does the substitution issuing a warning notice.