我的书有几个章节。每个章节里都有几个练习，每个练习都有答案，有些还附有提示。
本书的最后一章将收集提示和解决方案，按章节进行收集。
命令\printhint建议的这里一遍又一遍地打印所有提示。
所以我正在寻找一个命令或方法，可以只打印第 1 章的提示和第 2 章的提示等等。
一位 MWE 表示：
\documentclass[a4paper,openany]{book}
\usepackage{xsim}
\xsimsetup{
exercise/within = chapter,
}
% Add hints for the exercises
\DeclareExerciseProperty{hint}
\newcommand\hint[1]{\SetExerciseProperty{hint}{#1}}
\newcommand\printhints{%
\begin{description}
\ForEachUsedExerciseByType{%
\GetExercisePropertyT{hint}
{\item[Hint to~##3]####1}%
}%
\end{description}
}
\begin{document}
\chapter{Algebra}
\begin{exercise}[subtitle={Real numbers}]
Explain why the real numbers form a field.
\end{exercise}
\begin{solution}
Since addition and multiplication are defined and have the usual properties.
\end{solution}
\begin{exercise}
Explain what is a prime number.
\hint{a natural number greater than 1}
\end{exercise}
\begin{solution}
It is not a product of two smaller natural numbers.
\end{solution}
\chapter{Geometry}
\begin{exercise}[subtitle={Pythagoras' theorem}]
Prove that the area of the square whose side is the hypotenuse is equal to the sum of the areas of the squares on the other two sides.
\hint{Draw the altitude from point C, and call H its intersection with the side AB.}
\end{exercise}
\begin{solution}
The proof is easy.
\end{solution}
\begin{exercise}[subtitle={Thales's theorem}]
If A, B, and C are distinct points on a circle where the line AC is a diameter, the angle ABC is a right angle.
\end{exercise}
\begin{solution}
Since the sum of the angles in a triangle is equal to $180$\ldots
\end{solution}
\chapter*{Hints and solutions}
\section*{Hints to exercises from chapter 1}
\printhints %All of them are printed <<<
\section*{Solutions to exercises from chapter 1}
\printsolutions[headings=false,chapter=1]
\section*{Hints to exercises from chapter 2}
\printhints %They are all printed again, not good <<<
\section*{Solutions to exercises from chapter 2}
\printsolutions[headings=false,chapter=2]
\end{document}
答案1
请注意，##3参数的形式为\thechapter.\theexercise，因此我们可以提取章节编号并检查它是否等于“\printhints”的参数。
编辑
似乎你可以得到练习所在章节的编号值\ExercisePropertyGet，所以一个更简单的解决方案是
\documentclass[a4paper,openany]{book}
\usepackage{xsim}
\xsimsetup{
exercise/within = chapter,
}
% Add hints for the exercises
\DeclareExerciseProperty{hint}
\newcommand\hint[1]{\SetExerciseProperty{hint}{#1}}
\newcommand\printhints[1]{%
\begin{description}
\ForEachUsedExerciseByType{%
\GetExercisePropertyT{hint}
{%
\ifnum \ExercisePropertyGet{##1}{##2}{chapter-value}=#1
\item[Hint to~##3]####1
\fi
}%
}%
\end{description}
}
\begin{document}
\chapter{Algebra}
\begin{exercise}[subtitle={Real numbers}]
Explain why the real numbers form a field.
\end{exercise}
\begin{solution}
Since addition and multiplication are defined and have the usual properties.
\end{solution}
\begin{exercise}
Explain what is a prime number.
\hint{a natural number greater than 1}
\end{exercise}
\begin{solution}
It is not a product of two smaller natural numbers.
\end{solution}
\chapter{Geometry}
\begin{exercise}[subtitle={Pythagoras' theorem}]
Prove that the area of the square whose side is the hypotenuse is equal to the sum of the areas of the squares on the other two sides.
\hint{Draw the altitude from point C, and call H its intersection with the side AB.}
\end{exercise}
\begin{solution}
The proof is easy.
\end{solution}
\begin{exercise}[subtitle={Thales's theorem}]
If A, B, and C are distinct points on a circle where the line AC is a diameter, the angle ABC is a right angle.
\end{exercise}
\begin{solution}
Since the sum of the angles in a triangle is equal to $180$\ldots
\end{solution}
\chapter*{Hints and solutions}
\section*{Hints to exercises from chapter 1}
\printhints{1}
\section*{Solutions to exercises from chapter 1}
\printsolutions[headings=false,chapter=1]
\section*{Hints to exercises from chapter 2}
\printhints{2}
\section*{Solutions to exercises from chapter 2}
\printsolutions[headings=false,chapter=2]
\end{document}
在 expl3 的帮助下，您可以轻松地概括\printhints出以逗号分隔的章节编号列表，而不是一个数字。
\documentclass[a4paper,openany]{book}
\usepackage{xsim}
\xsimsetup{
exercise/within = chapter,
}
% Add hints for the exercises
\DeclareExerciseProperty{hint}
\newcommand\hint[1]{\SetExerciseProperty{hint}{#1}}
\ExplSyntaxOn
\NewDocumentCommand \printhints { m } {
\seq_set_split:Nnn \l_a_seq { , } { #1 }
\begin{description}
\ForEachUsedExerciseByType{
\GetExercisePropertyT{hint}
{
\seq_set_split:Nnn \l_b_seq { . } { ##3 }
\seq_get_left:NN \l_b_seq \l_a_tl
\seq_if_in:NVT \l_a_seq { \l_a_tl }
{
\item[Hint to~##3]####1
}
}
}
\end{description}
}
\ExplSyntaxOff
\begin{document}
\chapter{Algebra}
\begin{exercise}[subtitle={Real numbers}]
Explain why the real numbers form a field.
\end{exercise}
\begin{solution}
Since addition and multiplication are defined and have the usual properties.
\end{solution}
\begin{exercise}
Explain what is a prime number.
\hint{a natural number greater than 1}
\end{exercise}
\begin{solution}
It is not a product of two smaller natural numbers.
\end{solution}
\chapter{Geometry}
\begin{exercise}[subtitle={Pythagoras' theorem}]
Prove that the area of the square whose side is the hypotenuse is equal to the sum of the areas of the squares on the other two sides.
\hint{Draw the altitude from point C, and call H its intersection with the side AB.}
\end{exercise}
\begin{solution}
The proof is easy.
\end{solution}
\begin{exercise}[subtitle={Thales's theorem}]
If A, B, and C are distinct points on a circle where the line AC is a diameter, the angle ABC is a right angle.
\end{exercise}
\begin{solution}
Since the sum of the angles in a triangle is equal to $180$\ldots
\end{solution}
\chapter*{Hints and solutions}
\section*{Hints to exercises from chapter 1}
\printhints{1}
\section*{Solutions to exercises from chapter 1}
\printsolutions[headings=false,chapter=1]
\section*{Hints to exercises from chapter 2}
\printhints{2}
\section*{Solutions to exercises from chapter 2}
\printsolutions[headings=false,chapter=2]
\section*{Hints to exercises from chapters 1 and 2}
\printhints{1,2}
\end{document}
另一个选择是，第 n 次调用\printhints将打印第 n 章的提示
\documentclass[a4paper,openany]{book}
\usepackage{xsim}
\xsimsetup{
exercise/within = chapter,
}
% Add hints for the exercises
\DeclareExerciseProperty{hint}
\newcommand\hint[1]{\SetExerciseProperty{hint}{#1}}
\newcounter{hintchapcount}
\newcommand\printhints{%
\stepcounter{hintchapcount}
\begin{description}
\ForEachUsedExerciseByType{%
\GetExercisePropertyT{hint}
{%
\ifnum \ExercisePropertyGet{##1}{##2}{chapter-value}=\value{hintchapcount}
\item[Hint to~##3]####1
\fi
}%
}%
\end{description}
}
\begin{document}
\chapter{Algebra}
\begin{exercise}[subtitle={Real numbers}]
Explain why the real numbers form a field.
\end{exercise}
\begin{solution}
Since addition and multiplication are defined and have the usual properties.
\end{solution}
\begin{exercise}
Explain what is a prime number.
\hint{a natural number greater than 1}
\end{exercise}
\begin{solution}
It is not a product of two smaller natural numbers.
\end{solution}
\chapter{Geometry}
\begin{exercise}[subtitle={Pythagoras' theorem}]
Prove that the area of the square whose side is the hypotenuse is equal to the sum of the areas of the squares on the other two sides.
\hint{Draw the altitude from point C, and call H its intersection with the side AB.}
\end{exercise}
\begin{solution}
The proof is easy.
\end{solution}
\begin{exercise}[subtitle={Thales's theorem}]
If A, B, and C are distinct points on a circle where the line AC is a diameter, the angle ABC is a right angle.
\end{exercise}
\begin{solution}
Since the sum of the angles in a triangle is equal to $180$\ldots
\end{solution}
\chapter*{Hints and solutions}
\section*{Hints to exercises from chapter 1}
\printhints
\section*{Solutions to exercises from chapter 1}
\printsolutions[headings=false,chapter=1]
\section*{Hints to exercises from chapter 2}
\printhints
\section*{Solutions to exercises from chapter 2}
\printsolutions[headings=false,chapter=2]
\end{document}