Newcommand to replace defined words for gendering

Question

Following this thread new command with cases / conditionals / 'if… then's and the answer of Peter Grill I tried to change the example to another usecase: to make gendering more easy in my document.
There is a gender package available, but it does not provide what I need.

I setup the code in the following way, but I get always errors or the document is completely broken if it compiles (tried multiple things, like changing the "1" to an "m" – but obviously I have no clue what I am doing):

\documentclass{article}
\usepackage{xstring}

\newcommand{\genderhelp}[1]{%
\IfEqCase{#1}{%
        {experten}{Experten*innen}%
        {forscher}{Forscher*innen}%
        % you can add more cases here as desired
}[\PackageError{tree}{Undefined option to genderhelp: #1}{}]%
}%

\begin{document}
\genderhelp{experten}

\section{Die Hilfe von \genderhelp{forscher}}

\end{document}

So what I would like to achieve: give the command one word I already defined, and it outputs the defined string…
Of course I could go search and replace all over the document, but that seems not the right way to go – also e.g. if the writing with the "*" is not correct anymore, I would only have one place to change that.
And of course some more learning, how this Latex works 😉

Thanks a lot!

Answer 1

The obvious problem is that \genderhelp, as you defined it, is fragile. You can use \DeclareRobustCommand instead of \newcommand.

A better way is with expl3.

\documentclass{article}

%\usepackage{xparse} % uncomment for LaTeX prior to 2020-10-01

\ExplSyntaxOn
\NewDocumentCommand{\setgenderhelpers}{m}
 {
  \tl_gput_right:Nn \g_genderhelp_list_tl { #1 }
 }
\tl_new:N \g_genderhelp_list_tl

\NewDocumentCommand{\genderhelp}{m}
 {
  \str_case:nVF { #1 } \g_genderhelp_list_tl
   {
    \PackageError{tree}{Undefined option to genderhelp: #1}{}
   }
 }
\ExplSyntaxOff

\setgenderhelpers{
  {experten}{Experten*innen}
  {forscher}{Forscher*innen}
}

\begin{document}

\genderhelp{experten}

\section{Die Hilfe von \genderhelp{forscher}}

\end{document}

You see that the setting of the helpers is easier. With this approach you can define a list of helpers in the .sty file, but users can add to the list as needs arise using \setgenderhelpers in their document preamble.