Custom environment with full line width, even when put in e.g. enumerate

Question

I am writing a latex setup for exercise sheets.

I have defined a "solution" environment, that is only rendered if a boolean is set to true.

Sometimes, but not always, I will use a customised enumerate environment for different parts of an exercise. When i put the solution inside the enumerate, it will have a smaller linewidth.

How can i make it have the same linewidth as it would have outside of the enumerate?

MWE:

\documentclass[a4paper, 11pt]{article}
\usepackage{fullpage}
\usepackage{environ}
\usepackage{enumitem}
\usepackage{xcolor}
\setlength{\parindent}{0em}
\newcommand{\problem}[1]{\stepcounter{section}\section{Problem \sheetNr.\thesection: {#1}}}
\newenvironment{subproblems}{\enumerate[label=\textbf{\alph}.]}{\endenumerate}
\newif\ifanswers
\NewEnviron{solution}{
    \ifanswers
        \color{purple}
        \par\mbox{}\hrulefill\newline
        \textbf{Solution}:\
        %
        \expandafter\BODY
        %
    \fi
}
\newcommand{\sheetNr}{1}
\answerstrue
\begin{document}
    \problem{Some Title}
    A problem without subproblems
    \begin{solution}
        The solution has ``full" width.
    \end{solution}
\problem{Another Title}
\begin{subproblems}
    \item First part

    \begin{solution}
        This solution has reduced width
    \end{solution}

    \item Second Part
\end{subproblems}


\end{document}

You should have it \begin{enumerate}[wide]. B.t.w., for the labels formatting, it would be simpler to code [label=\alph*., font=\bfseries]. — Bernard, Nov 16 '20 at 19:52

score 0 · Accepted Answer · answered Nov 16 '20 at 20:19

If you're willing to adjust the input slightly - using \problem and \subproblem as commands rather than a command/environment approach, you can terminate the list after every \subproblem and use the enumitem-provided resume key to resume your sub-problem lists.

\documentclass{article}
\usepackage{environ}
\usepackage{enumitem}
\usepackage{xcolor}
\setlength{\parindent}{0pt}
\makeatletter
\def\restartlist{\relax}%
\setlist[enumerate,1]{before=\restartlist}
\newcommand{\problem}[1]{%
  \stepcounter{section}%
  \section{Problem \sheetNr.\thesection: #1}%
  \renewcommand{\restartlist}{\expandafter\setcounter\expandafter{@enumctr}{0}}% Restart numbering
}
\newcommand{\subproblem}[1]{%
  \begin{enumerate}[label=\textbf{\alph}.,resume]
    \item #1
  \end{enumerate}
  \renewcommand{\restartlist}{\relax}% Don't restart numbering
}
\newif\ifanswers
\NewEnviron{solution}{%
  \ifanswers
    \par
    \setlength{\parskip}{0pt}%
    \color{purple}%
    \leavevmode\hrulefill\par\nobreak
    \textbf{Solution}: \par\nobreak
    \BODY
  \fi
}
\newcommand{\sheetNr}{1}
\answerstrue
\begin{document}
\problem{First problem}
A problem without subproblems.
\begin{solution}
  The solution has ``full'' width.
\end{solution}
\problem{Second problem}
\subproblem{First part}
\begin{solution}
  This solution has ``full'' width.
\end{solution}
\subproblem{Second part}
\end{document}

If you wish to maintain the current input format (command \problem and environment subproblems), then you can capture the x-coordinate location and adjust the margins (using zref's savepos module and adjustwidth from changepage):

\documentclass{article}
\usepackage{environ}
\usepackage{enumitem}
\usepackage{xcolor}
\usepackage{changepage,zref-savepos}
\setlength{\parindent}{0pt}
\newcommand{\problem}[1]{\stepcounter{section}\section{Problem \sheetNr.\thesection: #1}}
\newenvironment{subproblems}{\enumerate[label=\textbf{\alph}.]}{\endenumerate}
\newif\ifanswers
\newcounter{curanswer}
\NewEnviron{solution}{%
  \ifanswers
    \par
    \stepcounter{curanswer}%
    \mbox{}\zsaveposx{leftmargin-\thecuranswer}%
    \par\vspace{\dimexpr-\parskip-\baselineskip}%
    \setlength{\parskip}{0pt}%
    \begin{adjustwidth}{\dimexpr\zposx{leftmargin}sp-\zposx{leftmargin-\thecuranswer}sp}{0pt}
      \color{purple}%
      \leavevmode\hrulefill\par\nobreak
      \textbf{Solution}: \par\nobreak
      \BODY
    \end{adjustwidth}
  \fi
}
\newcommand{\sheetNr}{1}
\answerstrue
\AtBeginDocument{%
  \zsaveposx{leftmargin}%
}
\begin{document}
\problem{First problem}
A problem without subproblems.
\begin{solution}
  The solution has ``full'' width.
\end{solution}
\problem{Second problem}
\begin{subproblems}
  \item First part
\begin{solution}
    This solution has ``full'' width.
  \end{solution}
\item Second part
\end{subproblems}
\end{document}

Thanks that works for me! I ended up making subproblem an environment, because the contents can become quite long.
May I ask why you end somelines with %? — Jakob Unfried, Nov 17 '20 at 15:35
@JakobUnfried: See What is the use of percent signs (%) at the end of lines? (Why is my macro creating extra space?). Also see How do you accept an answer? — Werner, Nov 17 '20 at 16:59

Custom environment with full line width, even when put in e.g. enumerate

1 Answers1