I would like to include a multicolumn-row in a tabular environment if \lehrertrue. Otherwise nothing should happen. I tried newcommand, newenvironment and NewEnviron and always end up with a "misplaced \omit". Apparently I am unable to convince \multicolumn that it is starting a new row.
My last try:
\documentclass[a4paper]{article}
\usepackage{environ}
\usepackage{t1enc}
\usepackage[cp437de]{inputenc}
\newif\iflehrer
\lehrertrue
\NewEnviron{lehrer}{\iflehrer{\multicolumn{5}{l}{\parbox{17cm}{\BODY}}}{{}}/fi}
\begin{document}
\begin{tabular}{rlccl}
1 & 2 & 3 & 4 & 5 \\
\begin{lehrer}
just a test\\
\end{lehrer}
1 & 2 & 3 & 4 & 5
\end{tabular}
\end{document}
Any helpful suggestions please?
P.S. I was unable to include something like "misplaced \omit" tag.
P.P.S. So far I have also been unable to find out whether nicematrix could solve the problem. "! LaTeX Error: Command \iint already defined. Or name \end... illegal, see p.192 of the manual."
\begingroupand this stops the lookup for\omit, so\multicolumnappears when the table cell has already started.nicematrix, your remark is rather strange because\nicematrixdoes not define any command\iint...