Babel: command for displaying current language

Question

I would like to know if there is some variable in LaTeX that stores the currently used language. The context is that I have some command, lets call it \printText which prints text in the current language. However, the command only has support for a few languages. Thus I would like to print an error message saying something like: <current language> is not supported by \printText.

Here is a MWE:

\documentclass{article}

\ExplSyntaxOn

\msg_new:nnnn { printText } { unsupported-language }
  { Language~`#1'~ not~ supported~ for~ ` \token_to_str:N \printText '. }
  { ` \token_to_str:N \printText '~ currently~ supports:~ english,~ spanish,~ norwegian~ and~ polish. }
 
\prop_new:N\g_vebjorn_text_prop
\prop_gset_from_keyval:Nn \g_vebjorn_text_prop
 {
   english = { This~ is~ a~ sentence },
   spanish = { Esta~es~una~frase },
   polish  = { To~jest~zdanie }
 }
\newcommand{\printText}
 {
   \prop_get:NVNTF \g_vebjorn_text_prop \languagename \l_tmpa_tl
     { \l_tmpa_tl }
     { \msg_error:nnn {printText} {unsupported-language} {current~ language} }
 }
\ExplSyntaxOff

% Babel may or may not be imported afterwards:
\usepackage[italian,polish]{babel}

\begin{document}
\selectlanguage{polish}
Hello.
\printText % If babel is not imported, this prints the english sentence.

\selectlanguage{italian}
Hello. 
\printText

\end{document}

I would like to change the {current~ language} in \msg_error:nnn {printText} {unsupported-language} {current~ language} to some variable (macro) that stores the current language used. Preferably, it should also work with \selectlanguage, so that it will display the active language used when calling the command.

Edit: \languagename does not work inside the error message, as it displays as Language `\languagename ' not supported . How can I make sure that \languagename displays correctly inside the error message?

Answer 1

I used \languagename instead of #1 in the error message and this worked.

\documentclass{article}

\ExplSyntaxOn

\msg_new:nnnn { printText } { unsupported-language }
  { Language~`\languagename'~ not~ supported~ for~ ` \token_to_str:N \printText '. }
  { ` \token_to_str:N \printText '~ currently~ supports:~ english,~ spanish,~ norwegian~ and~ polish. }
 
\prop_new:N\g_vebjorn_text_prop
\prop_gset_from_keyval:Nn \g_vebjorn_text_prop
 {
   english = { This~ is~ a~ sentence },
   spanish = { Esta~es~una~frase },
   polish  = { To~jest~zdanie }
 }
\newcommand{\printText}
 {
   \prop_get:NVNTF \g_vebjorn_text_prop \languagename \l_tmpa_tl
     { \l_tmpa_tl }
     { \msg_error:nn {printText} {unsupported-language} }
 }
\ExplSyntaxOff

% Babel may or may not be imported afterwards:
\usepackage[italian,polish]{babel}

\begin{document}
\selectlanguage{polish}
Hello.
\printText % If babel is not imported, this prints the english sentence.

\selectlanguage{italian}
Hello. 
\printText

\end{document}