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使命令健壯（牢不可破）

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使命令健壯（牢不可破）

如果您\bletter使用\DeclareRobustCommand\bletter[1]{\textbf{#1}}它進行定義，即使在部分命令中也可以正常運作。但是如果你想在\edefor\xdef命令中使用它，\bletter將會被破壞（除非你定義了\let\protect\noexpand）。這意味著：

\xdef\boldyletter{\bletter{y}}會拋出錯誤訊息。

有沒有什麼命令可以定義永遠牢不可破的命令？

答案1

您可以使用

\NewDocumentCommand\bletter{m}{\textbf{#1}}

這使得 e-tex \protected定義不會在 edef 中擴展。

但你不應該\xdef在未知的乳膠輸入上使用，使用\protected@xdef乳膠健壯的命令將受到保護。

答案2

只需使用\protected\def原語來聲明巨集\bletter：

\protected\def\bletter#1{\textbf{#1}}

在、、等期間巨集\protected不會展開。\edef\xdef\write\message

答案3

很抱歉回答我自己的問題，但我不知道如何與社區分享我的解決方案。

\def\RJDeclareRobustCommand#1% #1 name of new command, #2 same instructions as \newcommand
 {%
  \gdef#1%
   {%
    \begingroup%
     \let\relax\aftergroup% this has to be redefined before processing \csname @\string#1\endcsname
     \ifx\aftergroup\relax% this is false in expandations
      \expandafter\aftergroup\csname RJ@\expandafter\@gobble\string#1\endcsname%
     \else%  \expandafter\aftergroup\expandafter\noexpand\csname\expandafter\@gobble\string#1@RJ\endcsname%
     \fi%
    \endgroup%
   }%
  \expandafter\gdef\csname\expandafter\@gobble\string#1@RJ\endcsname%
   {%
    \begingroup%
     \let\relax\aftergroup% this has to be redefined before processing \csname @\string#1\endcsname
     \ifx\aftergroup\relax% this is false in expandations
      \expandafter\aftergroup\csname RJ@\expandafter\@gobble\string#1\endcsname%
     \else%
      \expandafter\aftergroup\expandafter\aftergroup\expandafter\aftergroup%
       \expandafter\noexpand\csname\expandafter\@gobble\string#1@RJ\endcsname%
     \fi%
    \endgroup%
   }%
%  read the instructions (see \new@command)
  \expandafter\new@command\csname RJ@\expandafter\@gobble\string#1\endcsname%
 }%
%

\RJDeclareRobustCommand\bletter[1]{\textbf{#1}}會很健壯。

\xdef\boldyletter{\bletter{y}}即使在命令中也能正常運作\xdef\boldxyletter{x\boldyletter}}。

答案4

非常感謝您提供的非常有幫助的答案。它們對我來說也是一個挑戰，我很高興地接受了。

為了在章節標題中使用新命令，除其他外，有必要在 \pdfstringdef 中新增和重新定義該命令。我的舊程式碼中沒有考慮到這一點。當添加這個需求時，我還能夠優化程式碼。

下面是使用新程式碼的測試範例。書籤中將忽略新指令，而不是其參數。

\documentclass[a4paper,12pt]{report}
\RequirePackage[pdftex,colorlinks,linkcolor=blue,%
                urlcolor=blue,bookmarksnumbered]{hyperref}
%
\makeatletter
%
\let\RJ@aftergroup\aftergroup%
\let\RJ@begingroup\begingroup%
\let\RJ@endgroup\endgroup%
\let\RJ@let\let%
%
\@ifundefined{pdfstringdefPreHook}{}%
 {%
  \gdef\Addpdfstringdef#1%
   {%
    \global\@temptokena\expandafter%
     {\pdfstringdefPreHook#1}%
    \xdef\pdfstringdefPreHook{\the\@temptokena}%
   }%     
%     
  \Addpdfstringdef%
   {%
    \let\RJ@aftergroup\@empty%
    \let\RJ@begingroup\@empty%
    \let\RJ@endgroup\@empty%
    \let\RJ@let\@empty%%
   }%  
 }% 
%
\def\RJ@DRCentry#1%
 {%
  \RJ@begingroup%
   \RJ@let\relax\RJ@aftergroup%
   \ifx\RJ@aftergroup\relax% 
    \expandafter\RJ@aftergroup\csname RJ@\expandafter\@gobble\string#1\endcsname%
   \else%
    \expandafter\noexpand\csname RJ\expandafter\@gobble\string#1JR\endcsname%
   \fi%
  \RJ@endgroup%
 }%
%
\def\RJ@DeclareRobustCommand#1% #1 name of new command, #2 same instructions as \newcommand
 {%
  \gdef#1%
   {%
    \ifx\RJ@aftergroup\@empty%
    \else%
     \expandafter\RJ@DRCentry\expandafter#1%  
    \fi%
   }%
%
  \expandafter\gdef\csname RJ\expandafter\@gobble\string#1JR\endcsname%
   {%
    \ifx\RJ@aftergroup\relax%
     \gdef\next{\RJ@DRCentry{#1}}%
     \RJ@aftergroup\next%
    \else%
     \expandafter\noexpand\csname RJ\expandafter\@gobble\string#1JR\endcsname%
    \fi%
   }%
%
  \@ifundefined{pdfstringdefPreHook}{}%
   {%
    \expandafter\Addpdfstringdef\expandafter%
     {\expandafter\let\csname RJ\expandafter\@gobble\string#1JR\endcsname\@empty}%
     }%
    \expandafter\new@command\csname RJ@\expandafter\@gobble\string#1\endcsname%
 }%
%
\RJ@DeclareRobustCommand\iletter[1]{\textit{\huge #1}}%
%
\xdef\yiletter{\iletter{y}}%
\xdef\xyiletter{\iletter{x}\yiletter}%
\xdef\xyziletter{\xyiletter\iletter{z}}%
\xdef\jiletter{\iletter{j\iletter{i}}}%

\begin{document}

 \tableofcontents

 \newpage

 test \iletter{j\iletter{i}}, \jiletter{} test \iletter{a}, \yiletter, \xyiletter, \xyziletter{} test

 \section{italic \iletter{y}, \xyziletter}

  The following chapter heading is for comparison purposes only .

 \section{italic \textit{\huge y}, \textit{\huge xyz}}

  more text

\end{document}

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