Interaction between `saveto` and newly introduced `redirectlowerto`

[muzimuzhi]

The interaction between saveto and savelowerto is well documented and handled in code base, but the interaction between saveto and redirectlowerto which was newly introduced in v6.1.0 (https://github.com/T-F-S/tcolorbox/commit/4918308ef96e482e4ee0f1343e6fe8c96984bf71) is not.

Currently in v6.1.0, if redirectlowerto is used along with saveto,

• a warning about saveto and savelowerto is thrown

  Package tcolorbox Warning: 'saveto' and 'savelowerto' cannot be combined. I deactivate 'savelowerto' on input line 22.

• its savelowerto and no lower part typesetting features are deactivated
• its lowerbox=ignored feature is retained.

\documentclass{article}
\usepackage{tcolorbox}

\begin{document}
\setcounter{enumi}{1}
Test counter: \theenumi

\begin{tcolorbox}[saveto=\jobname_mysave1, savelowerto=\jobname_mysave2,
  title={\texttt{saveto} and \texttt{savelowerto}}]
  upper part
  \tcblower
  lower part \stepcounter{enumi}
\end{tcolorbox}
New value of test counter: \theenumi.

\IfFileExists{\jobname_mysave1}
  {\verbatiminput*{\jobname_mysave1}}
  {non-existent}
\IfFileExists{\jobname_mysave2}{}{\texttt{savelowerto} file doesn't exist.}

\begin{tcolorbox}[saveto=\jobname_mysave3, redirectlowerto=\jobname_mysave4,
  title={\texttt{saveto} and \texttt{redirectlowerto}}]
  upper part 2
  \tcblower
  lower part 2 \stepcounter{enumi}
\end{tcolorbox}
New value of test counter: \theenumi.

\IfFileExists{\jobname_mysave3}
  {\verbatiminput*{\jobname_mysave3}}
  {non-existent}
\IfFileExists{\jobname_mysave4}{}{\texttt{redirectlowerto} file doesn't exist.}
\end{document}

[muzimuzhi]

Assuming the current behavior is expected (except for the warning message), below is an attempt for better warning message(s). Documentation still need adaptions.

BTW, although it can be inferred from key descriptions "no default, initially empty", that an empty <file name> passed to one of saveto, savelowerto, and redirectlowerto will deactivate (or partially deactivate, for the last one) the effect of corresponding option, do users need a direct statement like "An empty <file name> deactivates ... ."?

Example patching \tcb@set@@upper@and@lower to give better warning message(s)

```tex \documentclass{article} \usepackage{tcolorbox} \usepackage{xpatch} \makeatletter \xpatchcmd\tcb@set@@upper@and@lower {% \ifx\kvtcb@savelowerto\@empty% \else% \tcb@warning{'saveto' and 'savelowerto' cannot be combined. I deactivate 'savelowerto'}% \tcbset{savelowerto=}% \fi% } {% \ifx\kvtcb@savelowerto\@empty% \else% \iftcb@redirectlowerto% \tcb@warning{% 'saveto' and 'redirectlowerto' cannot be combined.\MessageBreak I deactivate 'redirectlowerto' but retain its\MessageBreak 'lowerbox' setting}% \tcb@redirectlowertofalse% \tcbset{savelowerto=}% \else% \tcb@warning{% 'saveto' and 'savelowerto' cannot be combined.\MessageBreak I deactivate 'savelowerto'}% \tcbset{savelowerto=}% \fi% \fi% } {}{\PatchFailed} \makeatother \begin{document} \setcounter{enumi}{1} Test counter: \theenumi \begin{tcolorbox}[saveto=\jobname_mysave1, savelowerto=\jobname_mysave2, title={\texttt{saveto} and \texttt{savelowerto}}] upper part \tcblower lower part \stepcounter{enumi} \end{tcolorbox} New value of test counter: \theenumi. \IfFileExists{\jobname_mysave1} {\verbatiminput*{\jobname_mysave1}} {non-existent} \IfFileExists{\jobname_mysave2}{}{\texttt{savelowerto} file doesn't exist.} \begin{tcolorbox}[saveto=\jobname_mysave3, redirectlowerto=\jobname_mysave4, title={\texttt{saveto} and \texttt{redirectlowerto}}] upper part 2 \tcblower lower part 2 \stepcounter{enumi} \end{tcolorbox} New value of test counter: \theenumi. \IfFileExists{\jobname_mysave3} {\verbatiminput*{\jobname_mysave3}} {non-existent} \IfFileExists{\jobname_mysave4}{}{\texttt{redirectlowerto} file doesn't exist.} \end{document} ```

PDF output is the same as before, and the new warning message is

Package tcolorbox Warning: 'saveto' and 'redirectlowerto' cannot be combined.
(tcolorbox)                I deactivate 'redirectlowerto' but retain its
(tcolorbox)                'lowerbox' setting on input line 54.

[T-F-S]

OK, I will update the warning code and also add additional documentation for the next version. Thank you.

[T-F-S]

Done with https://github.com/T-F-S/tcolorbox/releases/tag/v6.2.0