Horde_Mime_Part::offsetSet PHP Method

    public function offsetSet($offset, $value)
    {
        if (is_null($offset)) {
            $this->_parts[] = $value;
            $this->_status |= self::STATUS_REINDEX;
        } elseif ($part = $this[$offset]) {
            if ($part->parent === $this) {
                if (($k = array_search($part, $this->_parts, true)) !== false) {
                    $value->setMimeId($part->getMimeId());
                    $this->_parts[$k] = $value;
                }
            } else {
                $this->parent[$offset] = $value;
            }
        }
    }