public function & HasValidator ($validatorNameOrInstance) {
		if (is_string($validatorNameOrInstance)) {
			$validatorClassName = $validatorNameOrInstance;
		} else if ($validatorNameOrInstance instanceof \MvcCore\Ext\Forms\IValidator) {
			$validatorClassName = get_class($validatorNameOrInstance);
		} else {
			return $this->throwNewInvalidArgumentException(
				'Unknown validator type given: `' . $validatorNameOrInstance 
				. '`, type: `' . gettype($validatorNameOrInstance) . '`.'
			);
		}
		$slashPos = strrpos($validatorClassName, '\\');
		$validatorName = $slashPos !== FALSE 
			? substr($validatorClassName, $slashPos + 1)
			: $validatorClassName;
		return isset($this->validators[$validatorName]);
	}