我的文档中使用了以下环境。如您所见，我使用 进行晦涩难懂的可选参数处理增加了很多不必要的复杂性\IfValueTF。有没有办法简化此代码，使其expl3“按照我的想法做”？我希望能够用类似 的方式来表达逻辑\begin{displayquote}[#1]，#1当它传递给 时，保留其值/无值状态displayquote。
\documentclass{article}
\usepackage{expl3,xparse,csquotes} \ExplSyntaxOn
\NewDocumentEnvironment { citeverse } { o } {
\IfValueTF{#1}
{\begin{displayquote}[#1]}
{\begin{displayquote}}
} {
\end{displayquote}
}
\NewDocumentEnvironment { citeverse* } { o } {
\IfValueTF{#1}
{\begin{citeverse}[#1]}
{\begin{citeverse}}
% make square paragraph
\setlength{\parindent}{0pt}
\setlength{\parskip}{.5\baselineskip}
\setlength{\parfillskip}{0pt}
\setlength{\emergencystretch}{.5\textwidth}
} {
\end{citeverse}
}
\NewDocumentEnvironment { pageverse } { o } {
\thispagestyle{empty}
\null
\vfill
\IfValueTF{#1}
{\begin{citeverse}[#1]}
{\begin{citeverse}}
} {
\end{citeverse}
\vfill
\null
}
\NewDocumentEnvironment { pageverse* } { o } {
\IfValueTF{#1}
{\begin{citeverse*}[#1]}
{\begin{citeverse*}}
} {
\end{citeverse*}
}
\ExplSyntaxOff
\begin{document}
\begin{citeverse}
Easy come, easy go.
\end{citeverse}
\begin{citeverse}[Winston Churchill]
You have enemies? Good.
That means you've stood up for something,
sometime in your life.
\end{citeverse}
\begin{citeverse*}
A bird in the hand beats two in the bush.
In other news, this needs to be made longer
to really show off the square paragraph functionality.
\end{citeverse*}
\begin{citeverse*}[Benjamin Disraeli]
Action may not always bring happiness;
but there is no happiness without action.
\end{citeverse*}
\begin{pageverse}
Coming with quotations is hard.
\end{pageverse}
\begin{pageverse}[Abraham Lincoln]
Tact is the ability to describe others as they see themselves.
\end{pageverse}
\begin{pageverse*}
This is supposed to be a really long quotation---one that fills an entire page,
but I've completely run out of axioms to use!
I can only take comfort in the trend that axioms are short and pithy.
\end{pageverse*}
\begin{pageverse*}[Albert Einstein]
Only one who devotes himself to a cause with
his whole strength and soul can be a true master.
For this reason mastery demands all of a person.
\end{pageverse*}
\end{document}
答案1
你可以抽象出这样的结构：
\documentclass{article}
\usepackage{expl3,xparse,csquotes}
\ExplSyntaxOn
\NewDocumentCommand{\DefineSubEnvironment}{ m m m m m m }
{
\NewDocumentEnvironment { #1 } { o }
{
#3
\IfValueTF{##1}{\begin{#2}[##1]}{\begin{#2}}
#4
}
{
#5
\end{#2}
#6
}
}
\DefineSubEnvironment { citeverse } { displayquote }
{ } % pre begin
{ } % after begin
{ } % pre end
{ } % after end
\DefineSubEnvironment { citeverse*} { citeverse }
{ } % pre begin
{ % after begin
% make square paragraph
\setlength{\parindent}{0pt}
\setlength{\parskip}{.5\baselineskip}
\setlength{\parfillskip}{0pt}
\setlength{\emergencystretch}{.5\textwidth}
}
{ } % pre end
{ } % after end
\DefineSubEnvironment { pageverse } { citeverse }
{ % prebegin
\clearpage
\thispagestyle{empty}
\vspace*{\fill}
}
{ } % after begin
{ } % pre end
{ % after end
\vspace*{\fill}
\clearpage
}
\DefineSubEnvironment { pageverse* } { citeverse* }
{ } % pre begin
{ } % after begin
{ } % pre end
{ } % after end
\ExplSyntaxOff
\begin{document}
\begin{citeverse}
Easy come, easy go.
\end{citeverse}
\begin{citeverse}[Winston Churchill]
You have enemies? Good.
That means you've stood up for something,
sometime in your life.
\end{citeverse}
\begin{citeverse*}
A bird in the hand beats two in the bush.
In other news, this needs to be made longer
to really show off the square paragraph functionality.
\end{citeverse*}
\begin{citeverse*}[Benjamin Disraeli]
Action may not always bring happiness;
but there is no happiness without action.
\end{citeverse*}
\begin{pageverse}
Coming with quotations is hard.
\end{pageverse}
\begin{pageverse}[Abraham Lincoln]
Tact is the ability to describe others as they see themselves.
\end{pageverse}
\begin{pageverse*}
This is supposed to be a really long quotation---one that fills an entire page,
but I've completely run out of axioms to use!
I can only take comfort in the trend that axioms are short and pithy.
\end{pageverse*}
\begin{pageverse*}[Albert Einstein]
Only one who devotes himself to a cause with
his whole strength and soul can be a true master.
For this reason mastery demands all of a person.
\end{pageverse*}
\end{document}