xcolor-仅当（非）单色时才打印？

Question

当我使用该xcolor包时，我可以传递选项monochrome，将所有颜色变为黑色。是否可以定义命令\mono，并且\notmono仅在给出/不给出选项单色时才打印其内容？

说，

\documentclass{report}
\usepackage[
% monochrome
]{xcolor}    
\newcommand{\notmono}[1]{???} % No idea how to define this
\newcommand{\mono}[1]{???} % No idea how to define this

\begin{document}

\mono{Print this only if option monochrome IS given to xcolor.}
\notmono{Print this only if option monochrome is NOT given to xcolor.}    

\end{document}

编辑：我可以定义

\newcommand{\mono}[1]{}
\newcommand{\notmono}[1]{#1}

以防我没有给出monochrome选择，并在必要时重新定义它们

\newcommand{\mono}[1]{#1}
\newcommand{\notmono}[1]{}

但我仍然想知道是否有更好的方法来做到这一点。

Answer 1

在 的代码中xcolor，有一个\newif命令\ifcolors@默认为 true，monochrome使用该选项时设置为 false。因此，您可以定义自己的命令\notmono并\mono进行检查\ifcolors@。

\documentclass{report}
\usepackage[
% monochrome
]{xcolor}
\makeatletter
\newcommand{\notmono}[1]{\ifcolors@#1\else\fi}
\newcommand{\mono}[1]{\ifcolors@\else#1\fi}
\makeatother

\begin{document}

\mono{Print this only if option monochrome IS given to xcolor.}
\notmono{Print this only if option monochrome is NOT given to xcolor.}    

\end{document}

上述示例输出

取消注释该monochrome选项，它会输出

正如预期的那样。

Answer 2

为了避免在/的参数包含不平衡的- - -表达式的情况下出现\if..- - \else-嵌套问题，您可以在吞噬/传递参数之间进行分叉：\fi\mono\notmono\if..\else\fi

\documentclass{report}
\usepackage[%
%monochrome
]{xcolor}

\makeatletter
\newcommand*{\mono}{\ifcolors@\expandafter\@gobble\else\expandafter\@firstofone\fi}
\newcommand*{\notmono}{\ifcolors@\expandafter\@firstofone\else\expandafter\@gobble\fi}
%\newcommand*{\notmono}{\expandafter\unless\mono}
\newcommand*\CheckWhetherMono{\ifcolors@\expandafter\@secondoftwo\else\expandafter\@firstoftwo\fi}
\makeatother

\begin{document}

\mono{Print this only if option monochrome IS given to xcolor.}
\notmono{Print this only if option monochrome is NOT given to xcolor.}

\CheckWhetherMono{Print this only if option monochrome IS given to xcolor.}%
                 {Print this only if option monochrome is NOT given to xcolor.}


Now the weird things that malevolent users might do:

\iftrue
\mono{\fi Print this only if option monochrome IS given to xcolor.}
\notmono{\fi Print this only if option monochrome is NOT given to xcolor.}

\iftrue
\CheckWhetherMono{\fi Print this only if option monochrome IS given to xcolor.}%
                 {\fi Print this only if option monochrome is NOT given to xcolor.}

\end{document}