How to make my unusual environment accept one argument?

Question

I cannot find a good title to express my question. Therefore, please parse the following code first.

Minimal Code

\documentclass[dvips,dvipsnames,cmyk,table]{book}
\usepackage[a5paper,margin=20mm]{geometry}
\usepackage{longtable,array,calc}

\usepackage{listings}
\lstset{basicstyle=\scriptsize,tabsize=3}

\usepackage{fancyvrb}
\fvset{tabsize=3}
\newcommand\gtemp[1]{&&#1\tabularnewline\hline}
\newcommand{\args}{}
\newenvironment{Row}[1]
    {\renewcommand{\args}{#1}\VerbatimEnvironment\begin{VerbatimOut}{\jobname.tmp}}
    {\end{VerbatimOut}\aftergroup\gtemp{\args}}

\newcolumntype{A}
{
  >{\begin{minipage}{0.3333\linewidth-2\tabcolsep-2\arrayrulewidth}\vspace{\tabcolsep}}%
  c%
  <{\vspace{\tabcolsep}\end{minipage}}%   
}

\newenvironment{ComparisonTable}%
{% 
    \begin{longtable}%
    {%
     |A<{\lstinputlisting{\jobname.tmp}}%
     |A<{\input{\jobname.tmp}}%
     |A%
     |%
    }%
    \hline\ignorespaces%
}%
{\end{longtable}}

\begin{document}
\begin{ComparisonTable}
%
% Row 1
\begin{Row}%
{
 This is a quadratic function.
}
\begin{equation}
 y=ax^2+bx+c
\end{equation}
\end{Row}
%
% Row 2
\begin{Row}{LaTeX in action}
\Huge\LaTeXe
\end{Row}
\end{ComparisonTable}
\end{document}

Objective

I want \Row to accept an argument such that I can change

\begin{Row}
\begin{equation}
 y=ax^2+bx+c
\end{equation}
\end{Row}

to

\begin{Row}{Some description...}
\begin{equation}
 y=ax^2+bx+c
\end{equation}
\end{Row}

How to do this?

Answer 1

OK, there are two problems with the code you posted: 1. \aftergroup can only put one token (here \gtemp) after the group, and your \renewcommand doesn't give a global redefinition, so it won't be in effect after the group. This works:

\documentclass[dvips,dvipsnames,cmyk,table]{book}
\usepackage[a5paper,margin=20mm]{geometry}
\usepackage{longtable,array,calc}

\usepackage{listings}
\lstset{basicstyle=\scriptsize,tabsize=3}

\usepackage{fancyvrb}
\fvset{tabsize=3}
\newenvironment{Row}[1]
    {\gdef\gtemp{&&#1\tabularnewline\hline}\VerbatimEnvironment\begin{VerbatimOut}{\jobname.tmp}}
    {\end{VerbatimOut}\aftergroup\gtemp}

\newcolumntype{A}
{
  >{\begin{minipage}{0.3333\linewidth-2\tabcolsep-2\arrayrulewidth}\vspace{\tabcolsep}}%
  c%
  <{\vspace{\tabcolsep}\end{minipage}}%   
}

\newenvironment{ComparisonTable}%
{% 
    \begin{longtable}%
    {%
     |A<{\lstinputlisting{\jobname.tmp}}%
     |A<{\input{\jobname.tmp}}%
     |A%
     |%
    }%
    \hline\ignorespaces%
}%
{\end{longtable}}

\begin{document}
\begin{ComparisonTable}
%
% Row 1
\begin{Row}%
{
 This is a quadratic function.
}
\begin{equation}
 y=ax^2+bx+c
\end{equation}
\end{Row}
%
% Row 2
\begin{Row}{LaTeX in action}
\Huge\LaTeXe
\end{Row}
\end{ComparisonTable}
\end{document}