Renewcommand \textspanish

Question

Let's say I write a LaTeX document that usually is compiled with xelatex (and polyglossia), but I'd like to have pdflatex (and babel) as a fallback (when I send it to someone who might not have xelatex installed). For this I'd write \textspanish{} in the document and I came up with the following redefinition (wrapped basically in if pdflatex):

\newcommand{\textspanish}[2][]{\foreignlanguage{spanish}{#2}}

This approach seems to work fine for most languages, but for some reason babel has already a \textspanish command defined. So I tried the same with \renewcommand but this went into infinite recursion or something (TeX capacity exceeded, sorry [grouping levels=255]) for a reason I don't understand.

Sample document (works with xelatex, fails with pdflatex):

\documentclass[english,]{article}
\usepackage{lmodern}
\usepackage{ifxetex,ifluatex}
\ifnum 0\ifxetex 1\fi\ifluatex 1\fi=0 % if pdftex
  \usepackage[shorthands=off,spanish,english]{babel}
  \newcommand{\textspanish}[2][]{\foreignlanguage{spanish}{#2}}
\else
  \usepackage{polyglossia}
  \setmainlanguage[]{english}
  \setotherlanguage[]{spanish}
\fi
\begin{document}

Hello \textspanish{Hola}

\end{document}

Answer 1

Here is a solution not requiring another package:

\documentclass[english]{article}
\usepackage{lmodern}
\usepackage{ifxetex,ifluatex}
\ifnum 0\ifxetex 1\fi\ifluatex 1\fi=0 % if pdftex\
  \usepackage[shorthands=off,spanish,main=english]{babel}
  \let\oritextspanish\textspanish
  \AddBabelHook{spanish}{beforeextras}
    {\renewcommand{\textspanish}{\oritextspanish}}
  \AddBabelHook{spanish}{afterextras}
    {\renewcommand{\textspanish}[2][]{\foreignlanguage{spanish}{##2}}}
\else
  \usepackage{polyglossia}
  \setmainlanguage[]{english}
  \setotherlanguage[]{spanish}
\fi
\begin{document}

Hello \textspanish{Hola n\sptext{os}}

\end{document}

An issue related to the main language is also fixed (and I wonder if [2][] is intended, because the optional argument is not used at all).

Answer 2

I'm not sure what you mean by “fallback”. The problem seems to be that with polyglossia a \textspanish command already exists as soon as you enable Spanish; the good news is that this command essentially does \foreignlanguage{spanish}.

The bad news is that babel-spanish defines \textspanish (I don't know why they chose this name) and there's essentially no hope of using it as you'd like.

Here's an example of how \textspanish is used in spanish.ldf, that also hints at what it does, that is, it does some setup:

203 \def\extrasspanish{%
204   \textspanish
205   \mathspanish
206   \ifx\shorthandsspanish\@empty
207     \expandafter\spanishdeactivate\expandafter{\es@shlist}%
208     \languageshorthands{none}%
209   \else
210     \shorthandsspanish
211   \fi}

The definition of \textspanish is made step by step, so it's not readily available. My opinion is that this should be an internal command (so with a different name), because it does nothing really useful at the user level (and it's not documented, by the way). But it would be quite complicated (and not portable across documents without also copying the patches), changing spanish.ldf macros so that they use a different name.

Conversely, polyglossia uses a consistent interface: for every language <language> loaded, one has \text<language> that's an abbreviation for \foreignlanguage{<language>} plus some adaptations for it doing the right thing also in context of right-to-left languages.

Answer 3

The main problem is that \textspanish is used in the language switching commands. so you can try something like this:

\documentclass[english,]{article}
\usepackage{lmodern}
\usepackage{ifxetex,ifluatex,xpatch}
\ifnum 0\ifxetex 1\fi\ifluatex 1\fi=0 % if pdftex\
  \usepackage[shorthands=off,spanish,english]{babel}
  \let\oritextspanish\textspanish
  \patchcmd\extrasspanish{\textspanish}{\oritextspanish}{}{}
  \patchcmd\noextrasspanish{\textspanish}{\oritextspanish}{}{}
  \renewcommand{\textspanish}[2][]{\foreignlanguage{spanish}{#2}}
\else
  \usepackage{polyglossia}
  \setmainlanguage[]{english}
  \setotherlanguage[]{spanish}
\fi
\begin{document}

Hello \textspanish{Hola}

\end{document}