src/Peach/DT/HttpDateFormat.php
public function formatDatetime(Datetime $d)
    {
        $d = $d->add("minute", $this->internalOffset);

        $format  = '';
        $format .= $this->getDayDescription($d->getDay()).', ';
        $format .= str_pad($d->get('date'), 2, '0', STR_PAD_LEFT) . ' ';
        $format .= $this->getMonthDescription($d->get('month'))   . ' ';
        $format .= str_pad($d->get('year'), 4, '0', STR_PAD_LEFT) . ' ';
        $format .= $d->formatTime() . ' ';
        $format .= 'GMT';
        return $format;
    }
public function formatDatetime(Datetime $d)
    {
        $d = $d->add("minute", $this->internalOffset);

        $format  = '';
        $format .= $this->getDayDescription($d->getDay()).', ';
        $format .= str_pad($d->get('date'), 2, '0', STR_PAD_LEFT) . ' ';
        $format .= $this->getMonthDescription($d->get('month'))   . ' ';
        $format .= str_pad($d->get('year'), 4, '0', STR_PAD_LEFT) . ' ';
        $format .= $d->formatTime() . ' ';
        $format .= 'GMT';
        return $format;
    }
この時刻の HTTP-date 表現を返します.

@param  Datetime $d 書式化対象の時間オブジェクト
@return string      この時刻の HTTP-date 表現