\docsvlist and nested functions: unwanted large spaces

Question

I would like to iterate through a comma separated list to translate some words. I already found how to do so using \docsvlist from the etoolbox package. However, there is a large space printed before the first word and between the words when there should only be a "normal" space after the printed comma. I think the problem comes from the nesting of the \ifstrequal commands used for the translation.

Below is a MWE including an example calling all the possible translations and another example calling only the first translation to show the impact of the nesting.

How can I avoid these additional spaces?

MWE

\documentclass{article}
\usepackage{etoolbox}
\begin{document}
\newcommand\TranslateAnimal[1]{
    \ifstrequal{#1}{Cat}{Chat}{
        \ifstrequal{#1}{Dog}{Chien}{
            \ifstrequal{#1}{Mouse}{Souris}{
                \ifstrequal{#1}{Bird}{Oiseau}{
                    \ifstrequal{#1}{Horse}{Cheval}{
                        #1 % If there is no known translation
    }}}}}
}

\newcommand{\TranslateAnimalList}[2][,]{
    \def\nextitem{\def\nextitem{#1}}% Separator
    \renewcommand*{\do}[1]{\nextitem\TranslateAnimal{##1}} % How to process each item
    \docsvlist{#2}% Process list
}

There are additional large spaces before the first word and after words: \TranslateAnimalList{Cat,Bird,Dog,Horse,Mouse,Seal,Donkey}

Compare with: \TranslateAnimalList{Cat,Cat,Cat,Cat,Cat,Cat,Cat} where there is only a large space before the first word


\end{document}

every end of line is a space and the space after #1 is a space so your \TranslateAnimal has 8 spaces, use % at ends of lines to comment them out, and remove the space after#1 — David Carlisle, Nov 11 '20 at 23:54
Thank you! I was always wondering why people where commenting end of lines... — AlMa, Nov 11 '20 at 23:56
See What is the use of percent signs (%) at the end of lines? (Why is my macro creating extra space?) for details. — Alan Munn, Nov 12 '20 at 00:46

score 2 · Accepted Answer · answered Nov 12 '20 at 09:23

Check the differences and look at What is the use of percent signs (%) at the end of lines? (Why is my macro creating extra space?)

\documentclass{article}
\usepackage{etoolbox}
\newcommand\TranslateAnimal[1]{%
  \ifstrequal{#1}{Cat}{Chat}{%
    \ifstrequal{#1}{Dog}{Chien}{%
      \ifstrequal{#1}{Mouse}{Souris}{%
        \ifstrequal{#1}{Bird}{Oiseau}{%
          \ifstrequal{#1}{Horse}{Cheval}{%
            #1% If there is no known translation
  }}}}}%
}
\newcommand{\TranslateAnimalList}[2][, ]{%
  \def\nextitem{\def\nextitem{#1}}% Separator
  \renewcommand*{\do}[1]{\nextitem\TranslateAnimal{##1}}% How to process each item
  \docsvlist{#2}% Process list
}
\begin{document}
The list is \TranslateAnimalList{Cat,Bird,Dog,Horse,Mouse,Seal,Donkey}.
Compare with \TranslateAnimalList{Cat,Cat,Cat,Cat,Cat,Cat,Cat}.
\end{document}

You can possibly appreciate a different implementation with expl3.

\documentclass{article}
%\usepackage{xparse} % not needed with LaTeX 2020-10-01 or later
\ExplSyntaxOn
\NewExpandableDocumentCommand{\TranslateAnimal}{m}
 {
  \str_case:nnF { #1 }
   {
    {Cat}{Chat}
    {Dog}{Chien}
    {Mouse}{Souris}
    {Bird}{Oiseau}
    {Horse}{Cheval}
   }
   { #1 } % no known translation
 }
\NewDocumentCommand{\TranslateAnimalList}{O{,~}m}
 {
  \seq_clear:N \l_tmpa_seq
  \clist_map_inline:nn { #2 }
   {
    \seq_put_right:Nn \l_tmpa_seq { \TranslateAnimal { ##1 } }
   }
  \seq_use:Nn \l_tmpa_seq { #1 }
 }
\ExplSyntaxOff
\begin{document}
The list is \TranslateAnimalList{Cat,Bird,Dog,Horse,Mouse,Seal,Donkey}.
Compare with \TranslateAnimalList{Cat,Cat,Cat,Cat,Cat,Cat,Cat}.
\end{document}

\docsvlist and nested functions: unwanted large spaces

1 Answers1