[OS X TeX] Tried comment environment in Memoir

Mon Apr 6 20:43:29 CEST 2009

All,

For those who have been following this thread, here is a post by  
Ulrich from comp.text.tex that I find very helpful. Much thanks to  
Ross and Ulrich for helping us with this project.

David wrote:
 > The only sore point in my eyes is having to defer the \end
 > {writeverbatim} into the backanswer environment

Most of the verbatimizing-environments "scan" their
verbatimized input for a string
"\end{<environment-name>}" which is constructed
from the current environment's name which is held in
the macro \@currenvir, which in turn is set by the
\begin-macro.
When defining other environments in terms of
memoir's or comment's verbatim-like-environments,
don't use within your environment the \begin{environment}
..\end{environment}-Syntax but call the underlying
\environment..\endenvironment-macros directly.

E.g., instead of

\newenvironment{myenvironment}{%
   \begin{writeverbatim}{myfile}%

}{%

   \end{writeverbatim}%

}

you'd better write:
\newenvironment{myenvironment}{%
   \writeverbatim{myfile}%

}{%
   \endwriteverbatim
}

This is explained, e.g., in the manuals of the
"verbatim"-package.
The former again executes the \begin-macro
and sets \@currenvir := writeverbatim
thus the \writeverbatim-mechanism scans for
\end{writeverbatim}.

The latter does not again execute the \begin-macro
and thus \@currenvir still is "myenvironment"
thus the \writeverbatim-mechanism scans for
\end{myenvironment}.

The following examole seems to work without problems.

Be aware that you cannot use your environments as
arguments of macros---e.g.,

   \@firstofone{%
     \begin{answer}
     <Answer>
     \end{answer}
   }%

will lead to errors.
Nesting these environments is impossible also.

Ulrich

\documentclass{memoir}
\usepackage{amsmath}
\usepackage{comment}
\chapterstyle{bianchi}

\newoutputstream{backansout}
\newoutputstream{solutionsout}

\newenvironment{Exercises}
{\openoutputfile{\jobname.backans}{backansout}
\openoutputfile{\jobname.solns}{solutionsout}}
{\closeoutputstream{backansout}
\closeoutputstream{solutionsout}}

\newcounter{exercise}[section]
\renewcommand{\theexercise}{\arabic{exercise}}

\newenvironment{exercise}%
{\refstepcounter{exercise}
\par\noindent\textbf{\theexercise}.}
{\par}

\makeatletter

\newenvironment{genericout}[1]{%
   \@bsphack
   \ifodd\theexercise
     \addtostream{#1}{\protect\begin{oddexercise}{\theexercise}}%
   \else
     \addtostream{#1}{\protect\begin{evenexercise}{\theexercise}}%
   \fi
   \def\genericoutfile{#1}%
   \writeverbatim{#1}%

}{%

   \endwriteverbatim
   \ifodd\theexercise
     \addtostream{\genericoutfile}{\protect\end{oddexercise}}%
   \else
     \addtostream{\genericoutfile}{\protect\end{evenexercise}}%
   \fi
   \@esphack

}

\newenvironment{backanswer}{%
   \genericout{backansout}%

}{%
   \endgenericout
}%

\newenvironment{solution}{%
   \genericout{solutionsout}%

}{%
   \endgenericout
}%

\newenvironment{oddexercise}[1]{\par\noindent\textbf{#1.}}{}
\newenvironment{evenexercise}[1]{\par\noindent\textbf{#1.}}{}
%\includecomment{oddexercise}
\excludecomment{evenexercise}

\begin{document}

\chapter{The Whole Numbers}

\section{Introduction to the Whole Numbers}

Now is the time for all good men to come to the aid of their country.
Now is the time for all good men to come to the aid of their country.
Now is the time for all good men to come to the aid of their country.
Now is the time for all good men to come to the aid of their country.
Now is the time for all good men to come to the aid of their country.
Now is the time for all good men to come to the aid of their country.

\subsection{Exercises}

\begin{Exercises}