public function days()
    {
        if (!isset($this->days)) {
            $clonedStart = clone $this->weekStart;
            $this->days = array();
            for ($i = 0; $i < 7; $i ++) {
                $thisDay = new Day($clonedStart);

                if (
                    $this->containingMonth
                    && $this->containingMonth->firstDay()->format('m') != $clonedStart->format('m')
                ) {
                    $thisDay->setIsOverflow(true);
                }

                $this->days[] = $thisDay;
                $clonedStart->modify('+1 day');
            }
        }
        return $this->days;
    }