xsim, babel and tikzcd clash: quotation marks

Question

I'm trying to write a simple commutative diagram like A \arrow[r, "f"] & B but I can't do it inside xsim's exercise environment (the combination of the exercise environment with the babel package, tikz package and quotation marks doesn't work).

Despite having tried everythting, I could only narrow down the problem. Could you help me with the last step of the puzzle?

PS: I leave a minimal example below of what worked and didn't work. Thank you for your help!

\usepackage{xsim}
\usepackage{tikz-cd}
\usepackage[portuguese]{babel}
\usetikzlibrary{babel}
\begin{document}
%With quotation marks, it works outside the exercise environment:
   $\begin{tikzcd} 
   A \arrow[r, "f"] & B
   \end{tikzcd}$
%Without quotation marks, it works inside the exercise environment (with ampersand replacement):
   \begin{exercise}
   $\begin{tikzcd}[ampersand replacement=&] 
   A \arrow[r] & B
   \end{tikzcd}$
   \end{exercise}
%With quotation marks, it doesn't work inside the exercise environment:
   \begin{exercise}
   $\begin{tikzcd}[ampersand replacement=&] 
   A \arrow[r, "f"] & B
   \end{tikzcd}$
   \end{exercise}
\end{document}

Answer 1

This is the same problem as in

• Problem bringing the commutative diagram inside the question and answer frame and
• \AtBeginEnvironment{tikzcd} hasn't any effect

Here are three solutions:

1. Use the use-files class option.

   This will write additional files for every exercise environment (though there are options to tidy up your document folder) but it allows you to use both " and & as if the CD were written in the normal part of the document.

2. Use

   \AtBeginEnvironment{exercise}{\shorthandoff{"}}
   

   to switch off the " shorthand inside the exercise environment:

   \documentclass{article}
   \usepackage{xsim}
   \usepackage{tikz-cd}
   \usepackage[portuguese]{babel}
   \usetikzlibrary{babel}
   \AtBeginEnvironment{exercise}{\shorthandoff{"}}
   \begin{document}
   \begin{exercise}
   % Need to use \babelshorthand{"-} instead of "-
   \begin{tikzcd}[ampersand replacement=\&]
   A \arrow[r, "f"] \& B
   \end{tikzcd}
   \end{exercise}
   \end{document}
   

   

   That's not really bad unless you need to use the shorthands often inside an exercise environment.

3. As an alternative, here's an implementation that does not need to turn off the " shorthand but uses ' instead of ".

   This is a TikZ-CD only solution and it also essentially disables the TikZ shorthand ' for swap inside the argument for \arrow but not as part of a label (as in 'f'').

   \documentclass{article}
   \usepackage{xsim}
   \usepackage{tikz-cd}
   \usepackage[portuguese]{babel}
   \usetikzlibrary{babel}
   \makeatletter
   \tikzcdset{
     every label/.prefix code=% disable ' first char again to allow ' = swap
       \pgfkeyslet{/handlers/first char syntax/\expandafter\meaning\string'}%
                  \pgfutil@undefined,
     execute before arrows={%
       \pgfkeyssetvalue{/handlers/first char syntax/\expandafter\meaning\string'}
                       {\tikzcd@forward@singlequotes}}}
   \def\tikzcd@forward@singlequotes#1{\tikzcd@forward@@singlequotes#1\pgf@stop}
   \def\tikzcd@forward@@singlequotes'#1'#2\pgf@stop{%
     \tikzcd@forward@quotes{"{#1}"#2}}
   \makeatother
   \begin{document}
   \begin{exercise}
   \begin{tikzcd}[ampersand replacement=&]
   A \arrow[r, 'f''] & B
   \end{tikzcd}
   \end{exercise}
   \end{document}