How to use \verb or something similar inside a \newcommand

Question

The command \displaygraphics[width-1in]{figure=some_fig.pdf} will display a graphic. Sometimes I want to typeset when I do not have the graphics files available, so I want to do something like:

\renewcommand{\includegraphics}[1][]{\verb|#2|}

The intention is that it will simply display the name of the file to be used, rather than try to display the graphic. Note graphics names have underscores, which is the reason I would want something like verbatim. So the command \renewcommand{\includegraphics}[1][]{#2} does not work.

Of course the solution above does not work either, since \verb cannot be used like this inside a \renewcommand. How do I do this?

Answer 1

The reason your redefinition doesn't work is that you are specifying the wrong number of arguments in the \renewcommand. If I understand your question correctly you just want filename placeholders for your images. Here's an example:

\documentclass{article}
\usepackage[]{graphicx}
\renewcommand\includegraphics[2][]{\begin{center}\texttt{\detokenize{#2}\end{center}}
\begin{document}
\begin{figure}
\includegraphics[width=\linewidth]{Path/to/your/image/file}
\caption{When I finally get the file this will be a cool image}
\end{figure}
\end{document}

Alternatively, you can use the [demo] option of graphicx which will replace any \includegraphics command with a black box as below. In this case, of course, you don't get the filenames printed out, but you also don't need to redefine \includegraphics.

Answer 2

There are a number of errors in your code:

\renewcommand{displaygraphics}[1][]{\verb|#2|}

1. The first argument to \renewcommand must be a macro name (with the backslash (fixed in the question).

2. The command to redefine is \includegraphics (fixed in the question)

3. The number of arguments should be 2, not 1: when another pair of brackets follows, the contents is the default value of the optional argument, which is denoted by #1 in the replacement text; you also want a mandatory argument, which makes two.

4. \verb cannot be used in the argument to another macro.

Solution:

\renewcommand{\includegraphics}[2][]{\texttt{\detokenize{#2}}}

This will also allow underscores.

Answer 3

What about first check \IfFileExists and if already there, simply \includegraphics or otherwise, for underscores and long paths as well, in teletype style, better use an \url?

\documentclass[twocolumn]{article}
\usepackage{url}
\usepackage{graphicx}
\parskip1em

\newcommand\extimg[1]{
\IfFileExists{#1}
{\includegraphics[width=.5\linewidth]{#1}} 
{\fboxsep1em\fbox{\parbox{\dimexpr.5\linewidth-2em}{\url{#1}}}}}

\begin{document}

Some already made image:

\extimg{/usr/local/texlive/2015/texmf-dist/tex/latex/mwe/example-image-a.jpg}

Some image to do:

\extimg{/home/Richard/my_funny/proyect/more_carpets/and_more/images/todo_tomorrow/my_image.jpg}

\end{document}