Only displaying the list of tables while at least a table exists

Question

How can i let Tex only display the list of tables if there exists at least one table and not if there's none?

Answer 1

You can save the meaning of \listoftables, make the macro a no-op, but then add at the beginning of the first table the instruction to write in the log file that \listoftables has to receive its original meaning.

With \AddToHookNext, this is executed just once.

\documentclass{article}

\makeatletter
\let\orig@listoftables\listoftables
\let\listoftables\relax
\AddToHookNext{env/table/begin}{%
  \write\@auxout{\global\let\string\listoftables\string\orig@listoftables}%
}
\makeatother

\begin{document}

\listoftables

\section{Test}

\begin{table}[htp]
There is a table
\caption{Test}
\end{table}

\begin{table}[htp]
There is a table
\caption{Test}
\end{table}

\end{document}

The .aux file contains

\relax 
\@writefile{toc}{\contentsline {section}{\numberline {1}Test}{1}{}\protected@file@percent }
\global \let \listoftables\orig@listoftables
\@writefile{lot}{\contentsline {table}{\numberline {1}{\ignorespaces Test}}{1}{}\protected@file@percent }
\@writefile{lot}{\contentsline {table}{\numberline {2}{\ignorespaces Test}}{1}{}\protected@file@percent }
\gdef \@abspage@last{1}

Note that \global is necessary, because the .aux file is read in a group.

If I comment out the two table environments, the output is

and no list of tables is produced.