How to allow exceptions to \MakeLowercase or alternative macro

Question

Please see attached mwe. How can we optionally protect characters or words from the effect of \MakeLowercase{}?

\documentclass{article}%
\def\thestring{A Pacific hurricane is a mature tropical cyclone that develops within the northeastern and central {P}acific {O}cean}
\begin{document}
\noindent\thestring.\
{\noindent}The expedition leader explained that \MakeLowercase{\thestring}.
\end{document}

See the textcase package, it has a similar macro which supports a NoCaseChange macro — daleif, Oct 03 '20 at 13:18

score 2 · Accepted Answer · edited Oct 03 '20 at 16:22

2

You can use the features of \text_lowercase:n of expl3:

\documentclass{article}
\usepackage{xparse}
\ExplSyntaxOn
\NewDocumentCommand{\Lower}{m}
 {
  \group_begin:
  \tl_put_right:Nn \l_text_case_exclude_arg_tl { \K }
  \text_lowercase:n { #1 }
  \group_end:
 }
\NewDocumentCommand{\K}{m}{#1}
\ExplSyntaxOff
\newcommand\teststring{A Pacific hurricane is a mature tropical cyclone that
  develops within the northeastern and central \K{Pacific Ocean}}
\begin{document}
\teststring.
The expedition leader explained that \Lower{\teststring}.
\end{document}

By itself \K does nothing else than deliver its argument, but it will do so only after \text_lowercase:n has done its job; adding \K to the list of excluded commands, does the trick.

The operation

\tl_put_right:Nn \l_text_case_exclude_arg_tl { \K }

could be also done once and for all:

\documentclass{article}
\usepackage{xparse}
\ExplSyntaxOn
\NewDocumentCommand{\Lower}{m}
 {
  \text_lowercase:n { #1 }
 }
\NewDocumentCommand{\K}{m}{#1}
\tl_put_right:Nn \l_text_case_exclude_arg_tl { \K }
\ExplSyntaxOff

You could also use K{P}acific \K{O}cean.

edited Oct 03 '20 at 16:22

Pablo González L

3,584

answered Oct 03 '20 at 14:40

egreg

1,121,712

Currently exploring proposed solution, where is \l_text_case_exclude_arg_tl defined? – John Chris Feb 27 '21 at 15:12
Compiles with article.cls. When not using article.cls, which dependencies are required? – John Chris Feb 27 '21 at 15:19
1

@JohnChris It's a token list variable provided by the expl3 kernel. This should be independent of the document class. – egreg Feb 27 '21 at 16:04
Thanks @egreg. Updated system, now all good. – John Chris Feb 27 '21 at 18:31

How to allow exceptions to \MakeLowercase or alternative macro

1 Answers1