如何在环境参数中包含标签？

Question 1

我不会重新发明轮子：定义类似定理的环境时有几个微妙之处，恐怕您的代码没有解决这些问题。有了amsthm您，您就有了很好的方法来管理它们。您可以使用cleveref它来添加标签。

我使用expl3键值系统的语法，因为它功能强大并且可以与语言的其他功能相结合，例如检查键是否已设置。

我们还可以想象一个抽象层，允许\NewTheorem命令执行类似的工作\newtheorem并应用下面概述的想法。

\documentclass{article}
\usepackage{amsthm}
\usepackage{cleveref}

\newtheorem{generalthm}{Theorem}[section]
\crefname{generalthm}{theorem}{theorems}
\Crefname{generalthm}{Theorem}{Theorems}

\ExplSyntaxOn
\NewDocumentEnvironment{theorem}{O{}}
 {
  \keys_set:nn { hannes/theorem } { #1 }
  \tl_if_empty:VTF \l__hannes_theorem_cite_tl
   { \generalthm }
   { \generalthm[\l__hannes_theorem_cite_tl] }
   \tl_if_empty:VF \l__hannes_theorem_label_tl { \l__hannes_theorem_label_tl }
 }
 {
  \endgeneralthm
 }

\keys_define:nn { hannes/theorem }
 {
  cite  .tl_set:N = \l__hannes_theorem_cite_tl,
  label .tl_set:N = \l__hannes_theorem_label_tl,
 }

\ExplSyntaxOff

\begin{document}

\section{Main results}

\begin{theorem}[label=\label{th1},cite=see \cite{author1}]
good idea
\end{theorem}

\begin{theorem}[label=\label{th2},cite=see \cite[page~42]{author1}]
good idea
\end{theorem}

\begin{theorem}[label=\label{th3}]
good idea
\end{theorem}

We see that \cref{th1} is important. But \cref{th2} is more important.
Not to mention \cref{th3}.

\begin{thebibliography}{1}

\bibitem{author1} A. Uthor, \emph{Nice paper}, Journal (\textbf{1}), 2022

\end{thebibliography}

\end{document}

我不会使用这样的键值语法，因为标准\label很容易输入：

\begin{theorem}[see \cite{author1}]\label{th1}
good idea
\end{theorem}

甚至更容易输入。

顺便说一句，我认为没有理由使用\NewEnviron。

这是抽象层。

\documentclass{article}
\usepackage{amsthm}
\usepackage{cleveref}

\ExplSyntaxOn

\NewDocumentCommand{\NewTheorem}{momo}
 {
  % define the inner theorem-like environment
  \IfNoValueTF { #4 }
   {% we possibly have the first optional argument
    \IfNoValueTF { #2 }
     {% no parent counter
      \newtheorem{#1@inner}{#3}
     }
     {
      \newtheorem{#1@inner}[#2@inner]{#3}
     }
   }
   {% second optional argument
    \newtheorem{#1@inner}{#3}[#4]
   }
  % take care of cleveref
  \use:e
   {
    \exp_not:N \crefname{#1@inner}{\text_lowercase:n { #3 }}{\text_lowercase:n { #3 }s}
    \exp_not:N \Crefname{#1@inner}{\text_titlecase:n { #3 }}{\text_titlecase:n { #3 }s}
   }
  % define the user level environment
  \NewDocumentEnvironment{#1}{O{}}
   {
    \keys_set:nn { hannes/theorem } { ##1 }
    \tl_if_empty:VTF \l__hannes_theorem_cite_tl
     { \begin{ #1@inner } }
     { \begin{ #1@inner } [\l__hannes_theorem_cite_tl] }
    \tl_if_empty:VF \l__hannes_theorem_label_tl { \l__hannes_theorem_label_tl }
   }
   {
    \end{#1@inner}
   }
 }
\keys_define:nn { hannes/theorem }
 {
  cite  .tl_set:N = \l__hannes_theorem_cite_tl,
  label .tl_set:N = \l__hannes_theorem_label_tl,
 }

\ExplSyntaxOff

\NewTheorem{theorem}{Theorem}[section]
\NewTheorem{definition}[theorem]{Definition}

\begin{document}

\section{Main results}

\begin{theorem}[label=\label{th1},cite=see \cite{author1}]
good idea
\end{theorem}

\begin{theorem}[label=\label{th2},cite=see \cite[page~42]{author1}]
good idea
\end{theorem}

\begin{definition}[label=\label{def1}]
A definition
\end{definition}

\begin{theorem}[label=\label{th3}]
good idea
\end{theorem}

We see that \cref{th1} is important. But \cref{th2} is more important.
Not to mention \cref{th3}. And we have \cref{th1,th2,th3}.
Also \cref{def1} is interesting.


\begin{thebibliography}{1}

\bibitem{author1} A. Uthor, \emph{Nice paper}, Journal (\textbf{1}), 2022

\end{thebibliography}

\end{document}

注意如何\cref呈现多个交叉引用。

Answer