src/Zend/Filter/Compress/Rar.php
public function compress($content)
    {
        $callback = $this->getCallback();
        if ($callback === null) {

            throw new Zend_Filter_Exception('No compression callback available');
        }

        $options = $this->getOptions();
        unset($options['callback']);

        $result = call_user_func($callback, $options, $content);
        if ($result !== true) {

            throw new Zend_Filter_Exception('Error compressing the RAR Archive');
        }

        return $this->getArchive();
    }
public function compress($content)
    {
        $callback = $this->getCallback();
        if ($callback === null) {

            throw new Zend_Filter_Exception('No compression callback available');
        }

        $options = $this->getOptions();
        unset($options['callback']);

        $result = call_user_func($callback, $options, $content);
        if ($result !== true) {

            throw new Zend_Filter_Exception('Error compressing the RAR Archive');
        }

        return $this->getArchive();
    }
Compresses the given content

@param  string|array $content
@return string