我编写了一个“高级”环境，但如果我将另一个环境放入其中，就会遇到问题：
\documentclass{article}
\usepackage{amsmath,amsfonts,amssymb,amsthm} % For math equations, theorems, symbols, etc
\usepackage{thmtools}
\newif\ifadvanced % advanced environment
\advancedtrue % comment out to hide advanced environments
\newcommand{\separator}{\noindent\makebox[\linewidth]{\rule{\linewidth}{0.4pt}}}
\newenvironment{advanced}{\ifadvanced\par\separator \small \fi}{\ifadvanced\\\separator\par\fi}
\declaretheoremstyle[%
spaceabove=-6pt,%
spacebelow=6pt,%
headfont=\normalfont\itshape,%
postheadspace=1em,%
qed=\qedsymbol%
]{myproofstyle}
\declaretheorem[name={Proof},style=myproofstyle,unnumbered,
]{advancedproof}
\begin{document}
\begin{advanced}
Inside advanced environment.
\begin{advancedproof}
inside proof
\end{advancedproof}
\end{advanced}
\end{document}
我可以通过在\end{advanced}和之间添加文本来解决这个问题\end{advancedproof}，但一定有更好的方法来解决这个问题。我似乎找不到答案，因为我尝试在环境中添加换行符，但没有成功。
更新
所提出的代码搞乱了没有内部环境的行为：
\documentclass{article}
\usepackage{amsmath,amsfonts,amssymb,amsthm} % For math equations, theorems, symbols, etc
\usepackage{thmtools}
\newif\ifadvanced % advanced environment
\advancedtrue % comment out to hide advanced environments
\newif\ifadvanced % advanced environment
\advancedtrue % comment out to hide advanced environments
\newcommand{\separator}{\noindent\makebox[\linewidth]{\rule{\linewidth}{0.4pt}}}
\newenvironment{advanced}{\ifadvanced\par\separator \small \fi}{\ifadvanced\vspace*{-1em}\separator\par\fi}
\declaretheoremstyle[%
spaceabove=-6pt,%
spacebelow=6pt,%
headfont=\normalfont\itshape,%
postheadspace=1em,%
qed=\qedsymbol%
]{myproofstyle}
\declaretheorem[name={Proof},style=myproofstyle,unnumbered,
]{advancedproof}
\begin{document}
\begin{advanced}
Inside advanced environment.
\begin{advancedproof}
inside proof
\end{advancedproof}
\end{advanced}
\begin{advanced}
Inside advanced environment. But without any other internal environment
\end{advanced}
\end{document}
答案1
您可以用以下内容替换您的代码。这只是转换\\为\vspace*{0pt}。
\documentclass{article}
\usepackage{amsmath,amsfonts,amssymb,amsthm} % For math equations, theorems, symbols, etc
\usepackage{thmtools}
\newif\ifadvanced % advanced environment
\advancedtrue % comment out to hide advanced environments
\newcommand{\separator}{\noindent\makebox[\linewidth]{\rule{\linewidth}{0.4pt}}}
\newenvironment{advanced}{\ifadvanced\par\separator \small \fi}{\ifadvanced\vspace*{0pt}\separator\par\fi}
\declaretheoremstyle[%
spaceabove=-6pt,%
spacebelow=6pt,%
headfont=\normalfont\itshape,%
postheadspace=1em,%
qed=\qedsymbol%
]{myproofstyle}
\declaretheorem[name={Proof},style=myproofstyle,unnumbered,
]{advancedproof}
\begin{document}
\begin{advanced}
Inside advanced environment.
\begin{advancedproof}
inside proof
\end{advancedproof}
\end{advanced}
\end{document}
更新：您的问题应该使用
\newenvironment{advanced}{\ifadvanced\par\separator \small \fi}{\ifadvanced\vspace*{-.75em}\par\separator\par\fi}