# Should [arabic,main=english]{babel} change the plain pagestyle?

This is a follow-on from Table of contents page's number doesnt match the numbering style when i use foreign language "arabic". There the OP had difficulties with the page numbers of entries in the ToC. This a slimmed down version of the MWE which shows the problem and a solution.

% tocarabicprob2.tex  (based on SE 586620)
\documentclass[12pt,a4paper,twoside]{book}
\usepackage[Bjornstrup]{fncychap}
\pagestyle{plain}

\makeatletter
\let\origpsplain\ps@plain
\makeatother

\usepackage[arabic,main=english]{babel}

%%%%% try with and without this (arabic babel changes the definition of the plain pagestyle)
\makeatletter
\let\ps@plain\origpsplain
\makeatother

\usepackage{comment}

\begin{document}
\nocite{*}
\frontmatter

\centerline{\textsc{Acknowledgment}}
First

\clearpage

\centerline{\textsc{Notation:}}
Note
\clearpage

% this was in the original but did not affect any numbering
\begin{comment}
\begin{otherlanguage}{arabic}
\begin{center}
\Large{الملخص}
\end{center}
\begin{center}
\large{وبنيته وبعض البنيات الجزئية فيه.}
\end{center}
\end{otherlanguage}
\end{comment}

\mainmatter

\chapter{Preliminaries and Basic Concepts about Algebras}
blah

\end{document}


The OP's problem was that the page numbers changed from Roman to Arabic numbers with no intent on the part of the OP.

The basic problem here is that \usepackage[arabic,main=english]{babel} redefines the plain pagestyle (as noted by @Davislor in his answer to the original question). Why should the package interfere with the pagestyle and what could/should be done about it?

• language files can redefine stuff. But this is not a babel problem, but a problem of arabic, and as this is basically unmaintained it is not something that can be easily changed or corrected. Mar 11, 2021 at 19:47
• This is verging on an opinion-based question, but keep in mind that authors might want to change the numerals, and it might be necessary to change the text direction for numbers in that package. Mar 11, 2021 at 19:47
• The pragmatic answer is: switch to fontspec and \babelprovide[import=ar]{arabic}. Mar 11, 2021 at 19:49