包 [日期時間] 不適用於

Question

以下是 SSCCE：

\documentclass{report}

\usepackage{datetime}
%\usepackage{titling} %if this line is uncommented compilation fails

\begin{document}
\newdate{date2}{08}{02}{2015}
\date{\displaydate{date2}}
foo
\end{document}

...上面的程式碼可以編譯，但如果套件中呼叫的行titling未註釋，則編譯失敗並顯示：

pdflatex esa-sre-gedais-sdp.tex
This is pdfTeX, Version 3.1415926-1.40.10 (TeX Live 2009/Debian)
entering extended mode
(./esa-sre-gedais-sdp.tex
LaTeX2e <2009/09/24>
Babel <v3.8l> and hyphenation patterns for english, usenglishmax, dumylang, noh
yphenation, loaded.
(/usr/share/texmf-texlive/tex/latex/base/report.cls
Document Class: report 2007/10/19 v1.4h Standard LaTeX document class
(/usr/share/texmf-texlive/tex/latex/base/size10.clo))
(/usr/share/texmf-texlive/tex/latex/datetime/datetime.sty
(/usr/share/texmf-texlive/tex/latex/fmtcount/fmtcount.sty
(/usr/share/texmf-texlive/tex/latex/base/ifthen.sty)
(/usr/share/texmf-texlive/tex/latex/graphics/keyval.sty)
(/usr/share/texmf-texlive/tex/latex/amsmath/amsgen.sty)
(/usr/share/texmf-texlive/tex/latex/fmtcount/fc-english.def)
(/usr/share/texmf-texlive/tex/latex/fmtcount/fc-USenglish.def)
No configuration file fmtcount.cfg found.
)) (/usr/share/texmf-texlive/tex/latex/titling/titling.sty)
(./esa-sre-gedais-sdp.aux))
! Incomplete \iffalse; all text was ignored after line 8.
<inserted text> 
                \fi 
<*> esa-sre-gedais-sdp.tex

? X
No pages of output.
Transcript written on esa-sre-gedais-sdp.log.
make: *** [all] Error 1

Answer 1

我不知道這兩個包在做什麼，但如果有疑問，請添加\protect.運行沒有錯誤：

\documentclass{report}

\usepackage{datetime}
\usepackage{titling} %if this line is uncommented compilation fails

\begin{document}
\newdate{date2}{08}{02}{2015}
\date{\protect\displaydate{date2}}
foo
\end{document}

Answer 2

該datetime軟體包對哪些命令應該健壯或不健壯有一個特殊的選擇。例如，它聲明\longdate,\shortdate和類似的命令是健壯的（它們可能不應該），但它不會做與\displaydate移動參數中可能使用的相同的事情。

所以包應該做

\DeclareRobustCommand*{\displaydate}[1]{%
\@ifundefined{date@#1@y}{%
\PackageError{datetime}{Date `#1' not defined}{}}{%
\formatdate{\csname date@#1@d\endcsname}{%
\csname date@#1@m\endcsname}{%
\csname date@#1@y\endcsname}}}

因為這個指令使用\formatdate它執行賦值並且在（重新）定義時沒有聲明為健壯（也是\PackageError罪魁禍首）。不幸的是，該包使用了\newcommand。

您可以透過以下方式解決該問題etoolbox：

\documentclass{report}

\usepackage{etoolbox}
\usepackage{datetime}
\usepackage{titling} %if this line is uncommented compilation fails

\robustify{\displaydate} % make \displaydate robust

\begin{document}
\newdate{date2}{08}{02}{2015}

\title{Title}
\author{Author}
\date{\displaydate{date2}}

\maketitle

foo

\end{document}

並將其報告給包作者。