public function usort($cmp_function)
    {
        $tmp = $this->getArrayCopy();
        $ret = usort($tmp, $cmp_function);

        $tmp = new self($tmp);
        $this->exchangeArray($tmp->getArrayCopy());

        return $ret;
    }
public function usort($cmp_function)
    {
        $tmp = $this->getArrayCopy();
        $ret = usort($tmp, $cmp_function);

        $tmp = new self($tmp);
        $this->exchangeArray($tmp->getArrayCopy());

        return $ret;
    }
public function usort ( $ cmp_function ) { $ tmp = $ this -> getArrayCopy ( ) ; $ ret = usort ( $ tmp , $ cmp_function ) ; $ tmp = new self ( $ tmp ) ; $ this -> exchangeArray ( $ tmp -> getArrayCopy ( ) ) ; return $ ret ; }
Adds usort as an instance method

@param callback $cmp_function Function to sort by
@return boolean
Adds usort as an instance method