Libertine and lettrine with pdflatex: strange error

Question

I have this package lettrex.sty

\NeedsTeXFormat{LaTeX2e}
%
\RequirePackage{%
lettrine,%
ifthen,%
}
%
\setcounter{DefaultLines}{3}
\renewcommand{\DefaultLoversize}{0.07}
%
\DeclareOption{Libertine-Initials}{%
%X \renewcommand{\DefaultOptionsFile}{Libertine-Initials-Lettrinex.cfg}%
  \let\OldLettrine\lettrine%
  \renewcommand{\lettrine}[3][]{%
     \OldLettrine[#1]{\libertineInitialGlyph{#2}}{\MakeLowercase{#3}}%
  }%
}

\ProcessOptions\relax%
\endinput

and this config file Libertine-Initials-Lettrinex.cfg

    \LettrineOptionsFor{A}{findent=-0.8em,nindent=0.5em,loversize=0.07,slope=0.6em}

When I compile pdflatex testL-In.tex

\documentclass[12pt]{article}
\usepackage[T1]{fontenc}
\usepackage{libertine}
\usepackage{blindtext}

\usepackage[Libertine-Initials]{lettrex}

\begin{document}
\lettrine{A}{is a letter of our alphabet}. \blindtext
\end{document}

then all seems OK. But when I remove the %X in lettrex.sty to enable the options for letter 'A', I get this error:

(./testL-In.aux) (./Libertine-Initials-Lettrinex.cfg)
! Missing \endcsname inserted.
<to be read again> 
                   \protect 
l.16 \lettrine{A}{is a letter of our alphabet}
                                              . \blindtext
? 

(/zfs/texlive/2022/texmf-dist/tex/latex/libertine/T1LinuxLibertineInitialsT-LF.
fd)
! Extra \endcsname.
\@lettrine ...er \ifx \csname l@#2-keys\endcsname 
                                                  \relax \gdef \l@LOKeys {}\...
l.16 \lettrine{A}{is a letter of our alphabet}
                                              . \blindtext
? 

Overfull \hbox (7.46712pt too wide) in paragraph at lines 16--17
[][]\T1/LinuxLibertineT-TLF/m/n/12 . Lorem ip-sum do-lor sit amet, con-sectetue
r
[1{/zfs/texlive/2022/texmf-var/fonts/map/pdftex/updmap/pdftex.map}]
(./testL-In.aux) ){/zfs/texlive/2022/texmf-dist/fonts/enc/dvips/libertine/lbtn_
ncsllp.enc}{/zfs/texlive/2022/texmf-dist/fonts/enc/dvips/libertine/lbtn_vsrqlo.
enc}{/zfs/texlive/2022/texmf-dist/fonts/enc/dvips/libertine/lbtn_76gpa5.enc}</z
fs/texlive/2022/texmf-dist/fonts/type1/public/libertine/LinLibertineIT.pfb></zf
s/texlive/2022/texmf-dist/fonts/type1/public/libertine/LinLibertineT.pfb>
Output written on testL-In.pdf (1 page, 119263 bytes).
Transcript written on testL-In.log.

Finally it does give me the Initial, but what is done wrong here?

Answer 1

There is no need to patch \lettrine, you can use the hooks provided by lettrine:

\begin{filecontents}{Libertine-Initials-Lettrinex.cfg}
\LettrineOptionsFor{A}{findent=-0.8em,nindent=0.5em,loversize=0.07,slope=0.6em}
\end{filecontents}

\documentclass[12pt]{article}
\usepackage[T1]{fontenc}
\usepackage{libertine}
\usepackage{blindtext}

\usepackage[optionsfile=Libertine-Initials-Lettrinex.cfg]{lettrine}
\renewcommand\LettrineFontHook{\libertineInitial}
\renewcommand\LettrineTextFont{\MakeLowercase}
\begin{document}

\lettrine{A}{IS A LETTER OF OUR ALPHABET}. %uppercase for demo
\blindtext
\end{document}

Answer 2

The problem is that the second argument is used to check whether the particular initial is associated to some code in the .cfg file and passing it \libertineInitialGlyph{<letter>} breaks.

You need to patch something else, namely \setupL@lbox, where the typeset initial is stored.

I don't think you really want \MakeLowercase for the second argument.

\NeedsTeXFormat{LaTeX2e}

\RequirePackage{lettrine}

\setcounter{DefaultLines}{3}
\renewcommand{\DefaultLoversize}{0.07}

\DeclareOption{Libertine-Initials}{%
  \renewcommand{\DefaultOptionsFile}{Libertine-Initials-Lettrinex.cfg}%
  \def\setupL@lbox{%
    \computeL@height
    \ifL@image
      \sbox{\L@lbox}{\LettrineImage{\l@initial}}%
    \else
      \compute@fontsize
      \sbox{\L@lbox}{\LettrineFont\libertineInitialGlyph{\l@initial}}%
    \fi
  }%
}

\ProcessOptions\relax

\endinput

Probably you can remove \LettrineFont.

Answer 3

You do not need to patch anything, just change your lettrex.sty file:

\begin{filecontents}{Libertine-Initials.cfg}
\LettrineOptionsFor{A}{findent=-0.8em,
    nindent=0.5em,loversize=0.07,slope=0.6em}
\end{filecontents}

\begin{filecontents}{lettrex.sty}
\NeedsTeXFormat{LaTeX2e}

\RequirePackage{%
  lettrine,%
  iftex,%
}

\setcounter{DefaultLines}{3}
\renewcommand{\DefaultLoversize}{0.07}

\DeclareOption{Libertine-Initials}{%
\renewcommand{\LettrineFontHook}{%
              \fontfamily{LinuxLibertineInitialsT-LF}}
\renewcommand{\DefaultOptionsFile}{Libertine-Initials.cfg}
}
\ifpdftex
  \DeclareOption{Libertine-Initials}{%
  \renewcommand\LettrineFontHook{%
               \fontfamily{LinuxLibertineInitialsT-LF}}
  \renewcommand{\DefaultOptionsFile}{Libertine-Initials.cfg}
  }
\else
  \DeclareOption{Libertine-Initials}{%
  \renewcommand\LettrineFontHook{\fontspec{LinLibertine_I.otf}}
  \renewcommand{\DefaultOptionsFile}{Libertine-Initials.cfg}
 }
\fi

\ProcessOptions\relax
\endinput
\end{filecontents}

\documentclass[12pt]{article}
\usepackage[T1]{fontenc}
\usepackage{libertine}
\usepackage{blindtext}
\usepackage[Libertine-Initials]{lettrex}

\begin{document}
\lettrine{A}{is a letter of our alphabet}. \blindtext
\end{document}

produces no error message and outputs

If you don't want small caps for the second argument of \lettrine, just add \renewcommand{\LettrineTextFont}{\relax}