Automatically turning tables into color boxes

Question

I am writing a document class. I'd like that table environments are automatically transformed with tcolorboxes. Specifically, I'd like that the code \begin{table} ... \end{table} produces a table looking like the second table (i.e., the one using a tcolorbox). Note that this requires to recover the caption and the label.

\documentclass{article}

\usepackage{tcolorbox,xcolor}
\newtcolorbox[blend into=tables]{tablebox}[1][]{%
  float=htb,
  sharp corners,
  colback=blue!5,
  colframe=blue!50!darkgray,
  capture=hbox,every float=\centering,#1}

\begin{document}

Table \ref{temperatures} uses a tcolorbox.

\begin{table}
  \caption{My table}\label{temperatures}
  \begin{center}
    \begin{tabular}{ll}
      \hline
      Paris & 21 degrees\\
      Berlin & 19 degrees\\
      \hline
    \end{tabular}
  \end{center}    
\end{table}


\begin{tablebox}[title={My table}, label={temperatures},code={\par\medskip}]
  \begin{tabular}{ll}
    \hline
    Paris & 21 degrees\\
    Berlin & 19 degrees\\
    \hline
  \end{tabular}
\end{tablebox}

\end{document}

Possibly helpful starting point: https://tex.stackexchange.com/a/84258/6621....? — cmhughes, May 19 '20 at 17:10

score 8 · Accepted Answer · 2020-05-22T06:30:37.933

This is an attempt to talk you out of this. But let me start with an in principle working prototype example.

\documentclass{article}
\usepackage{environ}
\usepackage{tcolorbox,xcolor}
\newtcolorbox[blend into=tables]{tablebox}[1][]{%
  float=htb,
  sharp corners,
  colback=blue!5,
  colframe=blue!50!darkgray,
  capture=hbox,every float=\centering,#1}
\makeatletter
\newsavebox\TabB@x
\newif\ifTab@hasTitle
\newif\ifTab@hasLabel
\tcbset{tab@title/.code={\ifTab@hasTitle
\tcbset{title=#1}%
\fi},tab@label/.code={\ifTab@hasLabel
\tcbset{label=#1}%
\fi}}
\NewEnviron{Table}[1][]{\begingroup
\gdef\@gtempa{\relax}%
\gdef\@gtempb{\relax}%
\global\Tab@hasTitlefalse
\global\Tab@hasLabelfalse
\renewcommand\caption[1]{\global\Tab@hasTitletrue\gdef\@gtempa{##1}}%
\renewcommand\label[1]{\global\Tab@hasLabeltrue\gdef\@gtempb{##1}}%
\begin{lrbox}\TabB@x
\BODY
\end{lrbox}%
\global\setbox\TabB@x\box\TabB@x
\endgroup
\begin{tablebox}[tab@title=\@gtempa, tab@label=\@gtempb,code={\par\medskip}]
\usebox\TabB@x
\end{tablebox}}
\makeatother

\begin{document}

Table \ref{temperatures} uses a tcolorbox.

\begin{Table}
  \caption{My table}
  \label{temperatures}
  %\begin{center}
    \begin{tabular}{ll}
      \hline
      Paris & 21 degrees\\
      Berlin & 19 degrees\\
      \hline
    \end{tabular}
  %\end{center}    
\end{Table}

Table \ref{lowtemperatures} has no title.

\begin{Table}
  \label{lowtemperatures}
    \begin{tabular}{ll}
      \hline
      Paris & 21 degrees\\
      Berlin & 19 degrees\\
      \hline
    \end{tabular}
\end{Table}

\begin{Table}
  \caption{Another table}
  \label{hightemperatures}
    \begin{tabular}{ll}
      \hline
      Paris & 21 degrees\\
      Berlin & 19 degrees\\
      \hline
    \end{tabular}
\end{Table}



% \begin{table}
%   \caption{My table}\label{temperatures}
%   \begin{center}
%     \begin{tabular}{ll}
%       \hline
%       Paris & 21 degrees\\
%       Berlin & 19 degrees\\
%       \hline
%     \end{tabular}
%   \end{center}    
% \end{table}
% 
% 
% \begin{tablebox}[title={My table}, label={temperatures},code={\par\medskip}]
%   \tcbset{title=pft}%
%   \begin{tabular}{ll}
%     \hline
%     Paris & 21 degrees\\
%     Berlin & 19 degrees\\
%     \hline
%   \end{tabular}
% \end{tablebox}
% 
\end{document}

So this works in principle. (Obviously I was not courageous enough to touch the table environment with a lower-case t, but in principle one could.) One could make \begin{center}...\end{center} work, too, by redefining \center and \endcenter, say, or putting the stuff in some appropriate box.

I did not do that for a reason: to show that there are things which work fine in one environment but less so in another. Trying to tackle all possible cases with LaTeX methods is very hard, or impossible, i.e. one will always find places where this breaks.

This is not to say that one cannot do a very good job at redefining these things. I just do not think one can do a perfect job. If you really want to go that way, here is a prototype that works in principle and shows one possible direction to go.

Thanks for that. When there is no \caption, the table has "label" for the title. Is it possible to fix this? — user94293, May 22 '20 at 06:16
@user94293 Good point! Yes, one can fix that one. Please see the update. — , May 22 '20 at 06:31
By default (if option detach title is not used), tcolorbox stores the value passed to title option in \kvtcb@title, and detects if \kvtcb@title is empty when output. So you can store the argument of \caption directly in \kvtcb@title and skip the if-empty test. — muzimuzhi Z, May 22 '20 at 10:14
@muzimuzhiZ Thanks for the suggestion! Yes, that is certainly a great trick. (At the same time it shows even more that there are pitfalls, what if some user decides to detach the title? What I want to say is that by redefining things you lose a lot of options. I have not even mentioned the possibility that some may want to use the caption package with \captionsetup{...}, which is yet another example of something that won't work with these hacks. So I personally would just use the OP's nice tablebox as is.) — , May 22 '20 at 18:10

Automatically turning tables into color boxes

1 Answers1

Linked