环境中的可选键值

Question

下面的 MWE 产生了以下图片：

我希望将制表符和间距参数声明为可选键值，以便语法如下所示：

\begin{tabbedenum}[tabs=2, spacing=3]

注意：tabbedenum环境来自这个答案。

\documentclass{article}

\usepackage[inline]{enumitem}
\usepackage{tabto}

\newenvironment{tabbedenum}[2][]
{\NumTabs{#2}\begin{enumerate*}[
before={\unskip\hspace{\dimexpr-\parindent-1pt}\tab},itemjoin={\tab},#1]}%
{\end{enumerate*}}

\usepackage{setspace}

\begin{document}

\begin{enumerate}
\item Some text.

\begin{spacing}{3}
\begin{tabbedenum}{2}
\item $\displaystyle\sum_{r=1}^{n}x_r + \displaystyle\sum_{r=1}^{n}y_r = \displaystyle\sum_{r=1}^{n}(x_r+y_r)?$
\item $\displaystyle\sum_{r=1}^{n}x_r \cdot \displaystyle\sum_{r=1}^{n}y_r = \displaystyle\sum_{r=1}^{n}(x_r\cdot y_r)?$
\item $\displaystyle\sum_{r=1}^{n}(c\cdot x_r) = \displaystyle c\cdot\sum_{r=1}^{n}x_r?$
\item $\displaystyle\sum_{r=1}^{n}x_r + \displaystyle\sum_{r=1}^{n}y_r = \displaystyle\sum_{r=1}^{n}(x_r+y_r)?$
\end{tabbedenum}
\end{spacing}

\item Some text.

\end{enumerate}


\end{document}

Answer 1

以下是使用l3keys和的方法environ：

\documentclass{article}

\usepackage[inline]{enumitem}
\usepackage{tabto}

\newenvironment{tabbedenum}[2][]
{\NumTabs{#2}\begin{enumerate*}[
before={\unskip\hspace{\dimexpr-\parindent-1pt}\tab},itemjoin={\tab},#1]}%
{\end{enumerate*}}

\usepackage{expl3}
\usepackage{environ}

\ExplSyntaxOn
\cs_new:Nn \geoff_tse_parse_begin:nn {
  \keys_set:nn { geoff/tse } { #1 }
  \geoff_tse_begin:VVVn
    \l_geoff_tse_spacing_tl \l_geoff_tse_tabs_tl \l_geoff_tse_enumopt_tl { #2 }
}
\cs_new:Nn \geoff_tse_begin:nnnn {
  \begin{spacing}{ #1 }
    \NumTabs{ #2 }
    \begin{enumerate*}[
        before={\unskip\hspace{\dimexpr-\parindent-1pt}\tab},
        itemjoin={\tab},
        #3]
      #4
    \end{enumerate*}
  \end{spacing}
}

\cs_generate_variant:Nn \geoff_tse_begin:nnnn { VVVn }
\cs_generate_variant:Nn \geoff_tse_parse_begin:nn { nV }

\tl_new:N \l_geoff_tse_tabs_tl
\tl_new:N \l_geoff_tse_spacing_tl
\tl_new:N \l_geoff_tse_enumopt_tl

\keys_define:nn { geoff/tse }{
  tabs    .tl_set:N  = \l_geoff_tse_tabs_tl,
  tabs    .initial:n = { 2 },
  spacing .tl_set:N  = \l_geoff_tse_spacing_tl,
  spacing .initial:n = { 3 },
  enumopt .tl_set:N  = \l_geoff_tse_enumopt_tl,
  enumopt .initial:n = { },
}

\NewEnviron{tabbedspacedenum}[1][]{
  \geoff_tse_parse_begin:nV { #1 } \BODY
}

\ExplSyntaxOff

\usepackage{setspace}

\begin{document}

\begin{enumerate}
\item Some text.

\begin{spacing}{3}
\begin{tabbedenum}{2}
\item $\displaystyle\sum_{r=1}^{n}x_r + \displaystyle\sum_{r=1}^{n}y_r = \displaystyle\sum_{r=1}^{n}(x_r+y_r)?$
\item $\displaystyle\sum_{r=1}^{n}x_r \cdot \displaystyle\sum_{r=1}^{n}y_r = \displaystyle\sum_{r=1}^{n}(x_r\cdot y_r)?$
\item $\displaystyle\sum_{r=1}^{n}(c\cdot x_r) = \displaystyle c\cdot\sum_{r=1}^{n}x_r?$
\item $\displaystyle\sum_{r=1}^{n}x_r + \displaystyle\sum_{r=1}^{n}y_r = \displaystyle\sum_{r=1}^{n}(x_r+y_r)?$
\end{tabbedenum}
\end{spacing}

\item Some text.

\end{enumerate}

\clearpage

\begin{enumerate}
\item Some text.

\begin{tabbedspacedenum}
\item $\displaystyle\sum_{r=1}^{n}x_r + \displaystyle\sum_{r=1}^{n}y_r = \displaystyle\sum_{r=1}^{n}(x_r+y_r)?$
\item $\displaystyle\sum_{r=1}^{n}x_r \cdot \displaystyle\sum_{r=1}^{n}y_r = \displaystyle\sum_{r=1}^{n}(x_r\cdot y_r)?$
\item $\displaystyle\sum_{r=1}^{n}(c\cdot x_r) = \displaystyle c\cdot\sum_{r=1}^{n}x_r?$
\item $\displaystyle\sum_{r=1}^{n}x_r + \displaystyle\sum_{r=1}^{n}y_r = \displaystyle\sum_{r=1}^{n}(x_r+y_r)?$
\end{tabbedspacedenum}

\item Some text.

\end{enumerate}

\clearpage

\begin{enumerate}
\item Some text.

\begin{tabbedspacedenum}[tabs=4,spacing=1]
\item $4 + 5 > 6$?
\item $2 + 2 > 4$?
\item $2 + 2 > 4$?
\item $2 + 2 > 4$?
\end{tabbedspacedenum}

\item Some text.

\end{enumerate}
\end{document}