hyphenrules and \hyphenation

[u-fischer]

The documentation of the experimental german patterns, dehyph-exptl, recommend to use \babelprovide{hyphenrules...} to activate the patterns. This works but disables the \hyphenation command, unless one explicitly reset the language:

\documentclass{article}
\usepackage[T1]{fontenc}
\usepackage[main=ngerman]{babel}
%\babelprovide[hyphenrules=ngerman-x-latest]{ngerman}
% \selectlanguage{ngerman}
\hyphenation{Steg-lei-tung}
\begin{document}
\showhyphens{Abendstern}
\showhyphens{Stegleitung}
\end{document}

Result as is:

\T1/cmr/m/n/10 Abends-tern     % old, wrong
\T1/cmr/m/n/10 Steg-lei-tung    % correct

Result with \babelprovide line

 \T1/cmr/m/n/10 Abend-stern  %new, correct
 \T1/cmr/m/n/10 Ste-glei-tung % wrong

Result with additional \selectlanguage

\T1/cmr/m/n/10 Abend-stern   %new, correct
\T1/cmr/m/n/10 Steg-lei-tung  %correct

[jbezos]

I'm not sure if \babelprovide should apply the patterns in addition to setting them. Note \hyphenation is not expected to always work (and this is the very reason \babelhyphenation was added):

\documentclass{article}
\usepackage[italian]{babel}

% \hyphenation{l’a-qui-la}  % Fails when not commented out

\begin{document}
\showhyphens{l’aquila}
\end{document}

But I will think about it.

[lemzwerg]

I have no opinion on that. However, it should be documented in case the current behaviour is desired.

[jbezos]

It's not desired in the sense ideally \hyphenation should always work. But it doesn't and it's one of the reasons the manual states “To set hyphenation exceptions, use \babelhyphenation”.

[lemzwerg]

I suggest to extend this sentence to

“To set hyphenation exceptions, use \babelhyphenation instead of \hyphenation.”

[jbezos]

@lemzwerg 👌 And I'll promote it to a note or even a warning.

[jbezos]

After two issues in the same direction, even if I'm not quite convinced, the hyphenation rules are selected and applied. This seems to be the expected behaviour.