我们如何解释这两个输出之间的差异，其中第二个输出}紧随其后\xspace？
平均能量损失
\documentclass{article}
\usepackage{xspace}
\usepackage[citestyle=authoryear]{biblatex}
\newcommand{\coolxspaceunprotected}{\ifhmode\unskip\xspace\fi}
\newcommand{\coolxspaceprotected}{{\ifhmode\unskip\xspace\fi}} % How to avoid the braces?
\newcommand{\spacetciteunprotected}{\coolxspaceunprotected\textcite}
\newcommand{\spacetciteprotected}{\coolxspaceprotected\textcite}
\begin{filecontents}{\jobname.bib}
@book{smith96,
author = {Smith, Adam},
year = {1996},
title = {Economy},
publisher = {My company}
}
\end{filecontents}
\addbibresource{\jobname.bib}
\begin{document}
\section{\spacetciteunprotected{smith96} and the blob hypothesis}
\section{\spacetciteprotected{smith96} and the blob hypothesis}
\end{document}
答案1
您的主要问题是您在 中添加了一个空格hmode，但就在 parindent（或 sec number）框之后，您hmode不想有空格。\xspace在这里没有帮助。你想看看后退不是向前，这避免在（节点类型 1）之后添加空格，hbox因此它会在字符之后添加空格。
\documentclass{article}
\usepackage[citestyle=authoryear]{biblatex}
\DeclareRobustCommand\coolspaceunprotected{%
\ifhmode\ifnum\lastnodetype=1 \else\unskip\unskip\space
\fi\fi}
\DeclareRobustCommand\spacetciteunprotected{\coolspaceunprotected\textcite}
\begin{filecontents}{\jobname.bib}
@book{smith96,
author = {Smith, Adam},
year = {1996},
title = {Economy},
publisher = {My company}
}
\end{filecontents}
\addbibresource{\jobname.bib}
\begin{document}
\tableofcontents
\section{\spacetciteunprotected{smith96} and the blob hypothesis}
a
\section{\textcite{smith96} and the blob hypothesis}
b
\section{Foo,\spacetciteunprotected{smith96} and the blob hypothesis}
c
\section{Foo,\textcite{smith96} and the blob hypothesis}
d
\end{document}