Cleveref's namecref usage in etoolbox' tests

Question

I am currently trying to create new commands to add the correct French article in front of the cross-references when required (for example "la figure XX" or "le chapitre XX").

My initial idea was to create commands like \acref and \Acref somehow like that:

\newcommand{\acref}[1]{%
\def\rtype{\namecref{#1}}% namecref will produce something like "figure"
\def\article{{\bf error:[\rtype](#1)} }% default value to help debugging
\ifstrequal{\rtype}{figure}{\def\article{la }}{}%
\article\cref{#1}\xspace
}

I also tried adding \expandafter around \ifstrequal like that:

\expandafter\ifstrequal\expandafter{\rtype}{figure}{\def\article{la }}{}%

And I tried some other combinations of commands that I do not master, with bad results.

All my attempts produced an invalid output, either always using the article for figure (as it is currently the only one I try to test) because both branches of the conditional statement are executed (with too much \expandafter) or it never enters the true branch.

Minimal compiling and not working example:

\documentclass{paper}

\usepackage{cleveref}
\usepackage{etoolbox}
\usepackage{xspace}

\crefname{figure}{figure}{figures} % instead of fig.

\newcommand{\acref}[1]{%
\def\rtype{\namecref{#1}}% namecref will produce something like "figure"
\def\article{{\bf error:[\rtype](#1)} }% default value to help debugging
\ifstrequal{\rtype}{figure}{\def\article{la }}{}%
\article\cref{#1}\xspace
}

\begin{document}
  \section{Title}
  \label{sec:title}

  \begin{figure}
    \caption{Caption}
    \label{fig:caption}
  \end{figure}

  Test with figure: \acref{fig:caption}. % should print "la figure" but prints error:...

  Test with section: \acref{sec:title}. % should print error:...
\end{document}

---

I read that etoolbox does not expand its arguments in most of its tests, including \ifstrequal. I had the idea to create a list containing the result of \namecref as there is \listeadd which expands its item argument and then test if that list contains the text "figure". However, when I tried (\listeadd{\mylist}{\namecref{#1}}), pdflatex stopped compiling and returned (filtered):

! Argument of \@firstoftwo has an extra }
! Paragraph ended before \@firstoftwo was complete.
! TeX capacity exceeded, sorry [parameter stack size=10000].

So, is \namecref unexpandable?

---

Really close questions that I failed to make work in my case:

• Comparing an argument to a string when argument is a result of a command with etoolbox
• https://latex.org/forum/viewtopic.php?t=22106

Answer 1

Welcome to TeX.SE. You can use \cref@gettype to get the type of a cleveref reference in a macro of your choice (\mycref@type in the code below), then execute special code depending on the result. \cref@gettype expects that the \r@〈reference〉@cref macro has already been defined, which is done when the \newlabel command present in the .aux file is executed after the first compilation run with the 〈reference〉 in question. Therefore, my code checks whether the \r@〈reference〉@cref macro is defined and if not, prints ?? in the document along with the usual message on the terminal and in the log file:

LaTeX Warning: Label(s) may have changed. Rerun to get cross-references right.

I removed the use of xspace in your code, because the original author of xspace nowadays advises against using it (moreover, as egreg pointed out, xspace wouldn't be useful here, since your macro takes an argument). I changed the fig:caption label to fig-caption, otherwise with cleveref and : as an active character,¹ you'll encounter problems. Please also note that I use amsthm for the theorem in the example. Should you use theorem environments defined with \newtheorem from the LaTeX kernel, you'd find that the cleveref type for theorems using a shared counter is not necessarily what you expect (you'd get the name of the shared counter instead of the “specific” name; this doesn't happen with amsthm theorem environments).

Finally, don't forget to load cleveref last! :-)

\documentclass{article}
\usepackage{expl3}
\usepackage{amsthm}             % only for the demo
%\usepackage{hyperref}          % usually last, but before cleveref
\usepackage{cleveref}           % load this package last

\newtheorem{theorem}{Théorème}

\crefname{figure}{figure}{figures}    % instead of fig.
\crefname{theorem}{théorème}{théorèmes}

\makeatletter
\ExplSyntaxOn
% Let's borrow \str_case:onF from expl3 (\cs_new_eq:NN is like \let but checks
% that the “destination” command name doesn't already exist).
\cs_new_eq:NN \mycref@str@oswitch \str_case:onF
\ExplSyntaxOff

\newcommand*{\acref}[1]{%
  \ifcsname r@#1@cref\endcsname
    \cref@gettype{#1}{\mycref@type}%
    \mycref@str@oswitch{\mycref@type}
      {{figure}{la }%
       {theorem}{le }%
%      {...}{...}% you can add as many cases as you want!
      }
      {\errmessage{%
         My package: unknown reference type for label '#1':
         '\unexpanded\expandafter{\mycref@type}'}%
      }%
  \else
    \G@refundefinedtrue
    \nfss@text{\reset@font\bfseries ??}%
    \@latex@warning{Reference `#1' on page \thepage\space undefined}%
  \fi
  \cref{#1}%
}
\makeatother

\begin{document}

  \section{Title}\label{sec-title}

  \begin{theorem}\label{th-some-theorem}
    This is a theorem.
  \end{theorem}

  \begin{figure}
    \centering X
    \caption{Caption}
    \label{fig-caption}
  \end{figure}

  Test with figure: \acref{fig-caption}.

  Test with theorem: \acref{th-some-theorem}.

% Test with section: \acref{sec-title}. % prints an error, as expected

\end{document}

If you uncomment the \usepackage{hyperref} line and recompile until LaTeX is happy (because of the change in \newlabel syntax this implies), you'll get:

---

Footnote

1. Which will normally be the case if you use \usepackage[french]{babel} with the pdfTeX engine.