sfWebResponse::addVaryHttpHeader PHP Method

    public function addVaryHttpHeader($header)
    {
        $vary = $this->getHttpHeader('Vary');
        $currentHeaders = array();
        if ($vary) {
            $currentHeaders = preg_split('/\\s*,\\s*/', $vary);
        }
        $header = $this->normalizeHeaderName($header);
        if (!in_array($header, $currentHeaders)) {
            $currentHeaders[] = $header;
            $this->setHttpHeader('Vary', implode(', ', $currentHeaders));
        }
    }