Q: Ignore command / Suppress multiple spaces How can I suppress multiple spaces in this example:
\documentclass{article}
\begin{document}
\newcommand*{\foo}[1]{dummy foo output}
Test this \foo{3} command.
% but now I want to ignore it completely
\renewcommand*{\foo}[1]{\relax}
Test this \foo{3} command.
% ...and have no multiple spaces between "this" and "command"
\end{document}

I want to completely ignore \foo (still leaving it in the source code).
Kind regards, Ivan

A: The LaTeX kernel has \@bsphack and \@esphack for this.
\documentclass{article}

\makeatletter
\newcommand{\kokanignore}{\@bsphack\@esphack}
\makeatother

\begin{document}

\newcommand*{\foo}[1]{dummy foo output}
Test this \foo{3} command.

\foo{3} xyz

% but now I want to ignore it completely
\renewcommand*{\foo}[1]{\kokanignore}
Test this \foo{3} command.
% ...and have no multiple spaces between "this" and "command"

\foo{3} xyz

\end{document}


