隐藏列表中的特定 \item

Question

我想隐藏\item列表中的某些内容。我目前的尝试：

\documentclass{article}

\usepackage{ifthen}

\newboolean{enablehide}
\setboolean{enablehide}{true}

\newcommand{\hideit}{%
    \ifthenelse{\boolean{enablehide}}{%
    \begingroup
    \setbox0\hbox\bgroup}{}
}

\newcommand{\showit}{\ifthenelse{\boolean{enablehide}}{%
    \egroup
    \setbox1\hbox{}%
    \ht1=\ht0
    \wd1=\wd0
    \dp1=\dp0
    \box1
    \endgroup}{}
}

\begin{document}
   \begin{enumerate}

\item   not hide
\hideit

\item   hide
\showit

\item   not hide    
\end{enumerate}
\end{document}

错误： 出了点问题 - 可能缺少 \ item。\ item h

Answer 1

这是一个可能的解决方案：您想要（可能）隐藏的项目以 为前缀\hideit。您可以将布尔值设置为 false，\showitems并且\hideit不会执行任何操作。

\documentclass{article}

\ExplSyntaxOn

\NewDocumentCommand{\hideit}{}
 {
  \gaweiliex_hide:
 }

\NewDocumentCommand{\hideitems}{}
 {
  \bool_set_true:N \l_gaweiliex_hide_bool
 }
\NewDocumentCommand{\showitems}{}
 {
  \bool_set_false:N \l_gaweiliex_hide_bool
 }

\bool_new:N \l_gaweiliex_hide_bool

\cs_new_protected:Nn \gaweiliex_hide:
 {
  \bool_if:NT \l_gaweiliex_hide_bool
   {
    \peek_regex_replace_once:nn
     % search \item followed by anything until finding
     % \item or \hideit or \end{<current environment>}
     { \c{item}.*?(\c{item}|\c{hideit}|\c{end}\{\u{@currenvir}\}) }
     % replace by the matching item
     { \1 }
   }
 }

\ExplSyntaxOff

\hideitems % initialize


\begin{document}

\begin{enumerate}
\item This is shown 1
\hideit\item This is hidden
\hideit\item This is also hidden
\item This is shown 2
\hideit\item This is hidden
\item This is shown 3
\hideit\item This is hidden
\end{enumerate}

\begin{itemize}
\item This is shown 1
\hideit\item This is hidden
\hideit\item This is also hidden
\item This is shown 2
\hideit\item This is hidden
\item This is shown 3
\hideit\item This is hidden
\end{itemize}

\showitems

\begin{enumerate}
\item This is shown 1
\hideit\item This is hidden
\hideit\item This is also hidden
\item This is shown 2
\hideit\item This is hidden
\item This is shown 3
\hideit\item This is hidden
\end{enumerate}

\begin{itemize}
\item This is shown 1
\hideit\item This is hidden
\hideit\item This is also hidden
\item This is shown 2
\hideit\item This is hidden
\item This is shown 3
\hideit\item This is hidden
\end{itemize}

\end{document}