\AddToNoCaseChangeList not working

[mrpiggi]

Brief outline of the bug

Either using pdflatex or lualatex both with the stable and the development version, \AddToNoCaseChangeList has no effect, although it's argument is added to \l_text_case_exclude_arg_tl.

Minimal example showing the bug

\listfiles
\RequirePackage{latexbug}
\documentclass{article}
\begin{document}
\def\DontChangeCase#1{\textit{#1}}
\MakeUppercase{This is \NoCaseChange{\DontChangeCase{obviously}} working.}
\AddToNoCaseChangeList{\DontChangeCase}
\MakeUppercase{This is \DontChangeCase{not} working!}

\expandafter\show\csname l_text_case_exclude_arg_tl\endcsname
\end{document}

Log file (required) and possibly PDF file

changecase.log

[davidcarlisle]

We should probably highlight this more, but the command needs to be protected

\documentclass{article}
\begin{document}
\protected\def\DontChangeCase#1{\textit{#1}}
\MakeUppercase{This is \NoCaseChange{\DontChangeCase{obviously}} working.}
\AddToNoCaseChangeList{\DontChangeCase}
\MakeUppercase{This is \DontChangeCase{not} working!}

\expandafter\show\csname l_text_case_exclude_arg_tl\endcsname
\end{document}

[FrankMittelbach]

or even test for the condition in \AddToNoCaseList as this is an easy to make user error.

[josephwright]

I guess because I always recommend document commands are protected I forgot about this. We could adjust such ath commands are added to the 'no expand' list too: that would avoid the issue.

[davidcarlisle]

@josephwright you mean support un \protected commands, as in the original example here?

[josephwright]

@davidcarlisle Yes

[FrankMittelbach]

but they are added, they are only not looked at because the expand away first or am I missing something?

[josephwright]

@FrankMittelbach I meant that expandable commands need to be in \l_text_expand_exclude_tl to avoid 'disappearing' in \text_expand:n, which all of the other \text... functions use up-front.

[FrankMittelbach]

@josephwright and that has no unwanted side effects in that just because you add a command to the "don't casechange" it suddenly stops expanding elsewhere?

[josephwright]

@FrankMittelbach There should not be, no

[FrankMittelbach]

@josephwright sorry, don't get it. \text_expand:n could be used in other places and there the expandable command added to \l_text_expand_exclude_tl would no longer expand or not? And that would be wrong just because I don't want it to expand in a case changer.

[josephwright]

@FrankMittelbach The idea of \l_text_expand_exclude_tl is to list things that 'look expandable' but should not be expanded. So when we apply \text_expand:n, anything in \l_text_expand_exclude_tl is left alone. What happens next is down to the consumer command, but typically I'd expect entries there to be no-ops in the general situation. So for example \NoCaseChange can be defined \def\NoCaseChange#1{#1} and appear in \l_text_expand_exclude_tl: in the case changer this token can then be picked up, in other places the fact it's not been 'expanded away' will not make a difference.

[davidcarlisle]

@josephwright I'm not sure I see that? if I have \def\Name#1{<#1>} and add it to No case change list, I may still want this to be expanded out by \text_expand:n for other contexts such as text purification, Of course depending on the consuming code such an expandable command may "just work" and so having it unexpanded may not be an issue, but it does seem to be a change.

[josephwright]

@davidcarlisle That's what I meant by 'consumer': \text_purify:n does exactly that, for example

[mrpiggi]

If the command in question must be protected, what about \AddToNoCaseChangeList{\thanks}? In general, if I wanted to use \AddToNoCaseChangeList with a command either from the kernel or a third-party package, it would be really a pain to search for it's definition and apply for example \robustify from etoolbox. Especially, if unwanted side-effects could occur by doing so.

[u-fischer]

\thanks is robust and it works:

\documentclass{jacow}
\AddToNoCaseChangeList{\thanks}
\begin{document}

\title{An outstanding Paper%
                \thanks{No funding for this paper}}

\author{A. N. Author, City, State, Country}

\maketitle

\end{document}

[mrpiggi]

\thanks is robust and it works:

Sorry, my bad. I tested with my classes where I redefined \thanks locally. Nevertheless, it would be very convenient, if AddToNoCaseChangeList could be used not only with protected commands.

BTW: Although it was quite hacky, previous it was possible to suppress case changing for a command with any arbitrary arguments by patching \@uclcnotmath. This is not possible anymore, right?

[davidcarlisle]

@mrpiggi you can (locally if necessary) define the command as something like \def\foo#1#2#3{\NoCaseChange{\realfoo{#1}{#2}{#3}}} which will make the three argument \foo grab all three arguments and guard them from the case changer.

[josephwright]

OK, we have two possible approaches:

1. Adjust \AddToNoCaseChangeList so it also adds to \l_text_expand_exclude_tl
2. Document that commands used here have to be robust

Preferences?

[stale]

This issue has been automatically marked as stale because it has not had recent activity.

[josephwright]

I've thought about this again: I'm going to fix from expl3.

[josephwright]

I'll close here once the next l3kernel release goes out (it will not need to wait for the Fall 2023 LaTeX2e release: once expl3 changes it will 'just happen').