ledpar vs. polyglossia: Problem with \begin{⟨lang⟩}…\end{⟨lang⟩}

Question

I got a little Problem with the combination of polyglossia and ledpar. First the example

\documentclass[11pt,a4paper]{scrartcl}
\usepackage{xltxtra}
\usepackage{libertine}
\usepackage{polyglossia}
    \setmainlanguage[spelling=new,babelshorthands=true]{german}
    \setotherlanguage{latin}
    \setotherlanguage[variant=poly]{greek}
\usepackage{ledmac,ledpar}% PROBLEM-LINE
\begin{document}
\minisec{german}
Weit hinten, hinter den Wortbergen, fern der Länder Vokalien und Konsonantien
leben die Blindtexte. Abgeschieden wohnen Sie in Buchstabhausen an der Küste
des Semantik, eines großen Sprachozeans.

\minisec{latin}
\begin{latin}
Ulpianus libro primo institutionum pr Iuri operam daturum prius nosse oportet,
unde nomen iuris descendat. est autem a iustitia appellatum: nam, ut eleganter
Celsus definit, ius est ars boni et aequi.
\end{latin}

\minisec{greek}
\begin{greek}
μῆνιν ἄειδε θεὰ Πηληϊάδεω Ἀχιλῆος οὐλομένην, ἣ μυρί' Ἀχαιοῖς ἄλγε'
ἔθηκε, πολλὰς δ' ἰφθίμους ψυχὰς Ἄϊδι προί̈αψεν ἡρώων
\end{greek}

\minisec{short-versions}
Hier steht etwas griechisches: \textgreek{Πηληϊάδεω}
\end{document}

Without the problem-line, which includes ledpar, every thing works fine but with it the foreign-language-environments I get the problem which leads to some extra-text (]latin or ]greek) in the PDF at the beginning of environment’s content.

There’s no problem with the short-versions \text⟨lang⟩.

Answer 1

The same problem was mentioned here: http://tug.org/pipermail/xetex/2010-June/017029.html

I proposed a document based patch:

\letcs\POLYselectlanguage{\string\selectlanguage}
\usepackage{ledmac}
\usepackage{ledpar}
\AtBeginDocument{
\renewcommand{\selectlanguage}[2][]{%
   \POLYselectlanguage[#1]{#2}%
   \ifledRcol
     \gdef\theledlanguageR{#2}%
   \else
     \gdef\theledlanguageL{#2}%
  \fi}
}

that, as the OP said, solved the problem. François Charette proposed a patch to ledpar and ledmac (http://tug.org/pipermail/xetex/2010-June/017067.html), but I don't know what happened later.

The patch proposed by François is to change some lines in ledpar.sty: lines 1481--1498

\AtBeginDocument{%
  \@ifundefined{bbl@main@language}{%
    \l@dusedbabelfalse
    \renewcommand*{\selectlanguage}[1]{}}{%
    \l@dusedbabeltrue
    \let\l@doldselectlanguage\selectlanguage
    \let\l@doldbbl@set@language\bbl@set@language
    \let\bbl@set@language\l@dbbl@set@language
    \renewcommand{\selectlanguage}[1]{%
      \l@doldselectlanguage{#1}%
      \ifledRcol \gdef\theledlanguageR{#1}%
      \else      \gdef\theledlanguageL{#1}%
      \fi}
    \renewcommand*{\l@duselanguage}[1]{%
      \l@doldselectlanguage{#1}}
    \gdef\theledlanguageL{\bbl@main@language}%
    \gdef\theledlanguageR{\bbl@main@language}%
}}

should become

\AtBeginDocument{
  \@ifundefined{xpg@main@language}{% 
    \@ifundefined{bbl@main@language}{% no babel, no polyglossia
      \l@dusedbabelfalse
      \renewcommand*{\selectlanguage}[1]{}%
      }{% else babel loaded
      \l@dusedbabeltrue
      \let\l@doldselectlanguage\selectlanguage
      \let\l@doldbbl@set@language\bbl@set@language
      \let\bbl@set@language\l@dbbl@set@language
      \renewcommand{\selectlanguage}[1]{%
        \l@doldselectlanguage{#1}%
        \ifledRcol \gdef\theledlanguageR{#1}%
        \else      \gdef\theledlanguageL{#1}%
        \fi}
      \renewcommand*{\l@duselanguage}[1]{%
        \l@doldselectlanguage{#1}}
      \gdef\theledlanguageL{\bbl@main@language}%
      \gdef\theledlanguageR{\bbl@main@language}%
      }%
    }{%else polyglossia loaded
      \apptocmd{\xpg@set@language}{%
        \ifledRcol \gdef\theledlanguageR{#1}%
        \else      \gdef\theledlanguageL{#1}%
        \fi}%
      \let\l@duselanguage\xpg@set@language
      \gdef\theledlanguageL{\xpg@main@language}%
      \gdef\theledlanguageR{\xpg@main@language}%
    }}

It's essentially the (document based) patch I suggested, but cleaner.

Answer 2

August 2011:

Maïeul Rouquette has updated the ledpar.dtx file in CTAN with the François Charette patch above. (See https://groups.google.com/d/topic/comp.text.tex/NCly-8DJtkM/discussion.) The newest version of ledpar.dtx, with this new patch, is

• 0.3c patch 0.4 (see http://www.ctan.org/pkg/ledpar)

With this version ledpar, Martin Scharrer's problem mentioned above is solved.

However, I've recently installed TeXlive 2011, and I note that it delivers ledpar.sty in version 0.3b, and it does not have the Charette patch. Until TeXlive 2011 updates this, you'll need to get and install version 0.3c manually.

Answer 3

Both, polyglossia and ledpar redefines \selectlanguage. The definition of ledpar "win" and is active in the document, but is has a different number of arguments: \renewcommand{\selectlanguage}[1] versus \renewcommand{\selectlanguage}[2][] from polyglossia.

You will need someone who understand what ledpar is trying to achieve by redefining \selectlanguage to solve the clash.