How to workaround conflict between greek and titlecaps?

Question

I need to load greek with babel to support Greek text, but I am also using titlecaps to capitalise certain heading text.

Unfortunately, it seems this combination is not compatible but I'm having trouble identifying the specific cause and figuring out a workaround.

\documentclass[greek,british]{article}
\usepackage{babel}
\usepackage{titlecaps}
\Addlcwords{of}

\begin{document}

    This is some text.

\end{document}

What is the best way to adapt this code so that it works properly?

In the example above, commenting out \Addlcwords{of} gets the code to compile. However, in my real example, this just results in a different error later in the code, and so on. So I'm pretty sure there is something systematic I'm doing wrong here. What is it?

Answer 1

It's the usual problem: the package uses \roman for representing a counter value in roman numerals, but the greek option to babel changes \roman into a non fully expandable command.

Unfortunately, \roman is used in almost all macros of titlecaps, so providing a patch means rewriting the package.

The workaround suggested by Manuel in comments may work, but it can break Greek text.

\documentclass{article}

\makeatletter
\let\latex@roman\@roman
\makeatother

\usepackage[greek,british]{babel}
\usepackage{titlecaps}

\makeatletter
\let\@roman\latex@roman
\makeatother

\Addlcwords{of}

\begin{document}

This is some text.

\end{document}

As a side note: the titlecaps package needs to be revised anyway, because several of its macros have unprotected end-of-lines in the definitions.

A series of patches to the commands of titlecaps that should give the right behavior seems to be as follows:

\documentclass{article}

\usepackage[greek,british]{babel}
\usepackage{titlecaps}
\usepackage{xpatch}

\makeatletter
\def\dopatch#1{\xpatchcmd{#1}{\roman}{\romannumeral\value}{}{}}
\dopatch\Addlcwords
\dopatch\add@lcword
\dopatch\seek@lcwords
\dopatch\seek@lcwords
\dopatch\seek@lcwords
\dopatch\seek@lcwords
\dopatch\titlecap
\dopatch\titlecap
\dopatch\titlecap
\dopatch\titlecap
\dopatch\titlecap
\dopatch\titlecap
\dopatch\title@string
\dopatch\title@string
\dopatch\title@string
\dopatch\parse@@@Block
\undef\dopatch
\makeatother

\Addlcwords{of}

\begin{document}

This is some text.

\end{document}

In this way all occurrences of \roman{<counter>} are changed into \romannumeral\value{<counter>} which is safe, because it expands to \romannumeral\c@<counter> and the search for a number ends there.

Update

With titlecaps version 1.2, released 2015/01/30, the issues have been solved and your original example will work unchanged.