环境作为本地命名空间

Question

我希望得到一些相当简单且可以描述但也许不可能得到的东西。

我想给宏提供多个定义（\U在我的情况下），以便根据环境它可以具有不同的含义。

我会得到enva，envb并且在某处有envc其他的定义\Ua，\Ub以便\Uc

  \begin{enva}
  Some text, \U some other texts
  \end{enva}

展开相同Some text, \Ua some other texts

Answer 1

您可以提供默认定义，\U并在环境启动时更新它。

\newcommand{\U}{default definition} % maybe issuing error
\newcommand{\Ua}{definition for enva}
\newcommand{\Ub}{definition for envb}
\newcommand{\Uc}{definition for envc}

\newenvironment{enva}
 {\renewcommand{\U}{\Ua}...}
 {...}
\newenvironment{envb}
 {\renewcommand{\U}{\Ub}...}
 {...}
\newenvironment{envc}
 {\renewcommand{\U}{\Uc}...}
 {...}

由于环境形成群体，因此一旦环境结束，重新定义也将结束其效果。

Answer 2

\documentclass{article}
\newcommand\Ua{AAA}
\newcommand\Ub{BBB}
\newcommand\Uc{CCC}
\newcommand\U{} % Check that \U is not in use
\newenvironment{enva}{\let\U\Ua}{}
\newenvironment{envb}{\let\U\Ub}{}
\newenvironment{envc}{\let\U\Uc}{}
\begin{document}
\begin{enva}
  Some text, \U\ some other texts
\end{enva}

\begin{envb}
  Some text, \U\ some other texts
\end{envb}

\begin{envc}
  Some text, \U\ some other texts
\end{envc}
\end{document}

Answer 3

也许用在环境之间变化的变量来定义。

\documentclass{scrartcl}

\usepackage{etoolbox}
\newrobustcmd\definevariable[2][]
  {\providecommand#2{\csuse{_\environmentvariable_\detokenize{#2}}}%
   \expandafter\newcommand\csname\detokenize{_#1_#2}\endcsname}

\definevariable[a]{\U}{whatever}
\definevariable[b]{\U}{whatever else}
\definevariable[c]{\U}[1]{\uppercase{#1}}

\newenvironment{enva}{\def\environmentvariable{a}}{}
\newenvironment{envb}{\def\environmentvariable{b}}{}
\newenvironment{envc}{\def\environmentvariable{c}}{}

\begin{document}

\begin{enva}
  Some text, \U\ some other texts
\end{enva}

\begin{envb}
  Some text, \U\ some other texts
\end{envb}

\begin{envc}
  Some text, \U{some} other texts
\end{envc}

\end{document}

Answer 4

比其他的复杂得多......

\documentclass{article}

\usepackage{ifthen}
\newboolean{insideA}
\setboolean{insideA}{false}
\newboolean{insideB}
\setboolean{insideB}{false}
\newboolean{insideC}
\setboolean{insideC}{false}


\newcommand{\U}{%
\ifthenelse{\boolean{insideA}}{%
  in A%
}{%
    \ifthenelse{\boolean{insideB}}{%
    in B%
    }{%
        \ifthenelse{\boolean{insideC}}{%
        in C%
        }{%
            default%
}}}}


\newenvironment{enva}{\setboolean{insideA}{true}}{\setboolean{insideA}{false}}
\newenvironment{envb}{\setboolean{insideB}{true}}{\setboolean{insideB}{false}}
\newenvironment{envc}{\setboolean{insideC}{true}}{\setboolean{insideC}{false}}

\begin{document}

Some text, \U\ some other texts

\begin{enva}
  Some text, \U\ some other texts
\end{enva}

\begin{envb}
  Some text, \U\ some other texts
\end{envb}

\begin{envc}
  Some text, \U\ some other texts
\end{envc}
\end{document}