☰

\begin 和 \end 中带有匹配括号的环境

tag-icon • tag-icon environments
\begin 和 \end 中带有匹配括号的环境

假设我在文档中有这种表达。

\multicolumn{8}{l}{%
\parbox{25em}{%
\begin{itemize}
\addtolength{\itemsep}{-1em}
\item foo
\item bar
\end{itemize}%
}}

我想定义一个新的环境，称之为“评论”，这样我就可以简单地写

\begin{comment}
\item foo
\item bar
\end{comment}

并产生相同的输出。我遇到的问题是，在开头打开的括号只在最后才匹配。如果我尝试以不着边际的方式定义新环境的“开始”部分，就会出现问题：

\newenvironment{comment}{%
  \multicolumn{8}{l}{%
  \parbox{25em}{%
  \begin{itemize}
  \addtolength{\itemsep}{-1em}
}

括号现在不平衡，如果我在环境“开始”部分的定义中平衡它们，我会得到错误的结果。

这是 MWE

    \documentclass{article}


\def\Boxes{%
  $\Box$ & $\Box$ & $\Box$ & $\Box$ & $\Box$ & $\Box$ & $\Box$%
}
\usepackage{fullpage}

\begin{document}

\begin{table}[h!]
  \begin{tabular}{l|ccccccc}
    & Tue & Wed & Thur & Fri & Sat & Sun & Mon\\
    \hspace{1em}B$^{\flat}$ Major & \Boxes\\

    \multicolumn{8}{l}{%
      \parbox{25em}{%
      \begin{itemize}
        \addtolength{\itemsep}{-1em}
      \item foo
      \item bar
\end{itemize}%
}}
\\
\end{tabular}
\end{table}
\end{document}

答案1

正如评论中所述，您可以在中收集环境。正如 Werner 和 Heiko 的评论中所述，您之前lrbox不能使用标准，因此这有点含糊其辞。\begin\multicolumn\begin

    \documentclass{article}
%! LaTeX Error: Command \Box not provided in base LaTeX2e.
% make supplied MWE processable, grumble
\usepackage{amssymb}

\def\Boxes{%
  $\Box$ & $\Box$ & $\Box$ & $\Box$ & $\Box$ & $\Box$ & $\Box$%
}
\usepackage{fullpage}

\makeatletter
% only need this for \begin{spanlist} syntax otherwise skip this and use
% \spanlist....\endspanlist
\let\oldbegin\begin
\let\oldend\end
\def\begin#1{%
  \expandafter\ifx\csname#1\endcsname\spanlist
    \expandafter\@firstoftwo
  \else
  \expandafter\expandafter\expandafter\oldbegin\expandafter\@gobble
  \fi
  \spanlist{#1}}
\def\end#1{%
  \expandafter\ifx\csname#1\endcsname\spanlist
    \expandafter\@firstoftwo
  \else
  \expandafter\expandafter\expandafter\oldend\expandafter\@gobble
  \fi
  \endspanlist{#1}}
% end of scary \begin/\end redefinition.
\makeatother

\newenvironment{spanlist}
 {\omit\begin{lrbox}{0}\begin{minipage}{25em}\begin{itemize}\addtolength{\itemsep}{-1em}}
 {\end{itemize}\end{minipage}\end{lrbox}%
  \span\multicolumn{7}{l}{\usebox{0}}}

\begin{document}

% never use[h] on its own
%\begin{table}[h!]
\begin{table}[htp!]
  \begin{tabular}{l|ccccccc}
    & Tue & Wed & Thur & Fri & Sat & Sun & Mon\\
    \hspace{1em}B$^{\flat}$ Major & \Boxes\\
\begin{spanlist}
      \item foo
      \item bar
\end{spanlist}
\\
\end{tabular}
\end{table}
\end{document}

相关内容