better handling of language options

ptbbeamer.cls

@@ -5,23 +5,21 @@
 
 \ProvidesClass{\PTB@classname}[2022/07/30 v1.0.0 PTB beamer class (RN)]
 
-\newcommand*\PTB@babel@options{}
+\newcommand*\PTB@tempa{}
+\newcommand*\PTB@tempb{}
+\newcommand*\PTB@tempc{}
 
-\DeclareOption{ngerman}{%
-  \edef\PTB@babel@options{english,main=\CurrentOption}
-  \PassOptionsToPackage{english,\CurrentOption}{translator}
-}
-\DeclareOption{german}{%
-  \edef\PTB@babel@options{english,main=\CurrentOption}
-  \PassOptionsToPackage{english,\CurrentOption}{translator}
-}
-\DeclareOption{english}{%
-  \edef\PTB@babel@options{ngerman,main=\CurrentOption}
-  \PassOptionsToPackage{ngerman,\CurrentOption}{translator}
-}
+% Default language should be `ngerman'
+\def\PTB@tempa{english}
+\def\PTB@tempb{english,ngerman}
+\@for\CurrentOption:=\@classoptionslist\do{%
+  \ifx\CurrentOption\PTB@tempa
+    \def\PTB@tempb{ngerman}% Only add `english' if not already present
+  \fi
+}%
+\edef\@classoptionslist{\PTB@tempb,\@classoptionslist}
 \DeclareOption*{\PassOptionsToClass{\CurrentOption}{beamer}}
-\ExecuteOptions{ngerman}
-\ProcessOptions\relax
+\ProcessOptions*\relax
 
 \RequirePackage{iftex}% 
 \iftutex% LuaTeX or XeTeX
@@ -33,14 +31,11 @@
   }  
 \fi
 
-\newcommand*\PTB@tempa{}
-\newcommand*\PTB@tempb{}
-\newcommand*\PTB@tempc{}
 \newif\if@PTB@finalpage \@PTB@finalpagefalse
 
-\RequirePackage[\PTB@babel@options]{babel}
 \LoadClass[onlytextwidth]{beamer}
 
+\RequirePackage{babel}
 \RequirePackage{amsmath}
 
 \RequirePackage{unicode-math}