（重新）定义新命令中的字符

Question

我以为我的问题很简单，但它并没有按照我想要的方式工作。我希望某个（新）命令在另一个（新）命令中重新定义。我认为 MWE 很清楚：

\documentclass[10pt]{article}
\usepackage{fontspec}
\newcommand{\transcr}[1]{\textit{#1}
    \renewcommand{\schwa}{\textsuperscript{ə}}}
\newcommand{\schwa}{ə}

\begin{document}
In normal context, \schwa\ appears as it should.\\
In a different place it needs to be \transcr{sup\schwa rscript}, but it isn't\\
And then it doesn't appear as it should in normal context anymore: \schwa.
\end{document}

得出以下结果：

我尝试交换 \newcommand 和 \renewcommand 命令，但没有得到好结果。我做错了什么？

Answer 1

我会\schwa用条件来定义：

\documentclass[10pt]{article}
\usepackage{fontspec}

\newcommand{\transcr}[1]{%
  \textit{\transcrtrue #1}%
}

\newif\iftranscr % starts out false
\DeclareRobustCommand{\schwa}{%
  \iftranscr\textsuperscript{ə}\else ə\fi
}

\begin{document}
In normal context, \schwa\ appears as it should.

In a different place it needs to be \transcr{sup\schwa rscript}, but it isn't

And then it doesn't appear as it should in normal context anymore: \schwa.

\end{document}

由于\transcrtrue是在 提供的群组内发布的\textit，因此其效果仅限于该群组内。

稍微不同的方法允许直接使用ə（但\schwa如果您愿意，也可以）：

\documentclass[10pt]{article}
\usepackage{fontspec}
\usepackage{newunicodechar}

\newcommand{\transcr}[1]{%
  \textit{\transcrtrue #1}%
}

\newif\iftranscr % starts out false
\newunicodechar{ə}{%
  \iftranscr\textsuperscript{ə}\else ə\fi
}
\newcommand{\schwa}{ə} % must be done _after_ \newunicodechar{ə}{...}

\begin{document}
In normal context, ə appears as it should.

In a different place it needs to be \transcr{supərscript}, but it isn't

And then it doesn't appear as it should in normal context anymore: ə.

\bigskip

In normal context, \schwa\ appears as it should.

In a different place it needs to be \transcr{sup\schwa rscript}, but it isn't

And then it doesn't appear as it should in normal context anymore: \schwa.

\end{document}

您还可以嵌套条件：

\documentclass[10pt]{article}
\usepackage{fontspec}
\usepackage{newunicodechar}

\newcommand{\transcr}[1]{%
  \textit{\transcrtrue #1}%
}
\newcommand{\phon}[1]{%
  \textbf{\phontrue #1}%
}

\newif\iftranscr % starts out false
\newif\ifphon % starts out false
\newunicodechar{ə}{%
  \iftranscr
    \textsuperscript{ə}%
  \else     
    \ifphon
      \textsubscript{/ə/}%
    \else
      ə%   
    \fi
  \fi
}
\newcommand{\schwa}{ə} % must be done _after_ \newunicodechar{ə}{...}

\begin{document}
In normal context, ə appears as it should.

In a different place it needs to be \transcr{supərscript}, and it is;        
likewise it could be \phon{supərscript}.

And then it doesn't appear as it should in normal context anymore: ə.

\end{document}

Answer 2

需要交换指令\textit{#1}和的顺序\renewcommand{\schwa}{\textsuperscript{ə}}。另外，这两条指令都需要包含在 TeX 组中，以限制 重定义的范围\schwa。

\newcommand{\transcr}[1]{%
    {\renewcommand{\schwa}{\textsuperscript{ə}}%
    \textit{#1}}}

---

完整的 MWE：

\documentclass{article}
\usepackage{fontspec}

\newcommand{\transcr}[1]{%
    {\renewcommand{\schwa}{\textsuperscript{ə}}%
    \textit{#1}}}
\newcommand{\schwa}{ə}

\begin{document}
In normal context, \schwa\ appears as it should.

In a different place it needs to be \transcr{sup\schwa rscript}, and now it does.

And when it reappears in normal context --- \schwa\ --- things are still OK.
\end{document}