How can I typeset a command and its literal equivalent in an environment?

Question

UPDATE: I've opened a follow-up question: How can I typeset an environment and its literal equivalent in an environment?

---

I would like to pass a command and arguments to an environment. The output should be threefold:

1. The literal command
2. The typeset version (how it should appear when used)
3. The definition of the command. (This is just a textual description of what the command is used for.)

My Attempt

For this example, I try to use the \key command provided by the menukeys package.

\documentclass{article}
\usepackage{fontspec}
\usepackage{environ}
\usepackage{marginnote}
\usepackage{menukeys}
\NewEnviron{command}[1]{% 
\par
\reversemarginpar\marginnote{\texttt{\string#1}}
\BODY
\par
\textbf{Example:} % And here is #1 with #2, but literally typeset (e.g. literally \keys{Shift + F5})
\par
%#1#2 % <-- I'd like to typeset these two inputs properly (e.g. non-literal \keys{Shift + F5})
\par
}%


\begin{document}

\begin{command}{\keys}% {{Shift + F5}} % Example input does not work
This command allows you to add keyboard strokes. % here is the definition followed by an example on the next line.
\end{command}

\end{document}

Desired Output

My Thoughts

Maybe this is not even the right approach. I do not know how to go about dealing the commands with multiple arguments efficiently (e.g. created with the xparse package).

Answer 1

You should absorb the two arguments verbatim, which xparse allows to do; then you can “rescan” the two arguments when you want to show the effect.

\documentclass{article}
\usepackage{fontspec}
\usepackage{menukeys}
\usepackage{xparse}

\ExplSyntaxOn
\NewDocumentEnvironment{command}{vv}
 {
  \tl_set:Nn \l_macmad_argument_i_tl { #1 }
  \tl_set:Nn \l_macmad_argument_ii_tl { #2 }
  \par
  \noindent
  \makebox[0pt][r]{\ttfamily\l_macmad_argument_i_tl\hspace{2em}}
  \ignorespaces
 }
 {
  \par\nopagebreak
  \noindent
  \textbf{Example:~}
  \texttt
   {
    \l_macmad_argument_i_tl
    \tl_if_blank:VF \l_macmad_argument_ii_tl
     { \{ \l_macmad_argument_ii_tl \} }
   }
  \\*
  \tl_set_rescan:NnV \l_macmad_argument_tl {} \l_macmad_argument_i_tl
  \tl_if_blank:VF \l_macmad_argument_ii_tl
   {
    \tl_set_rescan:NnV \l_macmad_temp_tl {} \l_macmad_argument_ii_tl
    \tl_put_right:Nx \l_macmad_argument_tl { { \exp_not:V \l_macmad_temp_tl } }
   }
  \l_macmad_argument_tl
  \par
 }
\tl_new:N \l_macmad_argument_tl
\tl_new:N \l_macmad_argument_i_tl
\tl_new:N \l_macmad_argument_ii_tl
\tl_new:N \l_macmad_temp_tl
\cs_generate_variant:Nn \tl_set_rescan:Nnn { NnV }
\ExplSyntaxOff

\begin{document}

\begin{command}{\keys}{Shift + F5}
This command allows you to add keyboard strokes.
\end{command}

\begin{command}{\TeX}{}
This command prints the \TeX\ logo.
\end{command}

\begin{command}{\textbf}{\TeX}
This command prints its argument in bold.
\end{command}

\end{document}

You can accommodate more than one argument, but in this case you need to use braces for the mandatory ones, even if there's only one of them.

\documentclass{article}
\usepackage{fontspec}
\usepackage{menukeys}
\usepackage{xparse} % but it's already loaded by fontspec

\ExplSyntaxOn
% "v" means "verbatim argument"
\NewDocumentEnvironment{command}{vv}
 {
  % store the two arguments in variables
  % xparse has absorbed them "verbatim"
  \tl_set:Nn \l_macmad_argument_i_tl { #1 }
  \tl_set:Nn \l_macmad_argument_ii_tl { #2 }
  \par
  \noindent
  % print the first argument in the margin
  \makebox[0pt][r]{\ttfamily\l_macmad_argument_i_tl\hspace{2em}}
  \ignorespaces
 }
 {
  \par\nopagebreak
  \noindent
  \textbf{Example:~}
  \texttt
   {
    % print the first argument
    \l_macmad_argument_i_tl
    % print the second argument (but only if non empty)
    \tl_if_blank:VF \l_macmad_argument_ii_tl
     { \l_macmad_argument_ii_tl }
   }
  \\*
  % transform back the first argument from verbatim into "standard tokens"
  \tl_set_rescan:NnV \l_macmad_argument_tl {} \l_macmad_argument_i_tl
  \tl_if_blank:VF \l_macmad_argument_ii_tl
   {
    % do the same for the second argument (if non empty)
    \tl_set_rescan:NnV \l_macmad_temp_tl {} \l_macmad_argument_ii_tl
    % append the rescanned text to the previous
    \tl_put_right:Nx \l_macmad_argument_tl { \exp_not:V \l_macmad_temp_tl }
   }
  % process the contents of the rescanned arguments
  \l_macmad_argument_tl
  \par
 }

% allocate the variables
\tl_new:N \l_macmad_argument_tl
\tl_new:N \l_macmad_argument_i_tl
\tl_new:N \l_macmad_argument_ii_tl
\tl_new:N \l_macmad_temp_tl
% generate a variant command
\cs_generate_variant:Nn \tl_set_rescan:Nnn { NnV }
\ExplSyntaxOff

\begin{document}

\begin{command}{\keys}{{Shift + F5}}
This command allows you to add keyboard strokes.
\end{command}

\begin{command}{\TeX}{}
This command prints the \TeX\ logo.
\end{command}

\begin{command}{\textbf}{{\TeX}}
This command prints its argument in bold.
\end{command}

\begin{command}{\framebox}{[3cm][l]{\TeX}}
This command frames text in a specified area.
\end{command}

\end{document}

Answer 2

Is not exactly what you asked, but may be is useful for someone. The advantage is that the tcolorbox package can print the LaTeX code and the result of this code in a environment with a lot of options.

\documentclass{article}
\usepackage[most]{tcolorbox}
\usepackage{menukeys}
\newtcblisting{command}{sidebyside,width=.55\linewidth,nobeforeafter,baseline=5mm,lefthand ratio=0.65}
\parskip1em
\begin{document}

Print the \TeX\ logo \dotfill \begin{command}\TeX\end{command} 

Add keyboard strokes \dotfill \begin{command}\keys{Shift + F5}\end{command}

Print argument in bold \dotfill \begin{command}\textbf{\TeX}\end{command}

\end{document}

Edit:

Another rigid but simple solution is the package example:

\documentclass[a5paper]{article}
\usepackage{menukeys,example,lipsum}
\parindent0in\parskip1em
\begin{document}

This command allows you to add keyboard strokes.%
\begin{example}
\keys{Shift + F5}
\end{example}

This command prints the \TeX\ logo.
\begin{example}
\TeX
\end{example}

This command prints its argument in bold.
\begin{example}
\textbf{\TeX}
\end{example}

This print a boxed dummy text.  

\begin{example}
\fbox{\begin{minipage}{4cm}
\raggedright
\tiny\lipsum[2]
\end{minipage}}
\end{example}

\end{document}

Answer 3

This should do as wanted, and also allows multiple arguments. The only problem is that if there are control sequences in the second argument they are appended with a space.

\documentclass{article}
\usepackage{fontspec}
\usepackage{environ}
\usepackage{marginnote}
\usepackage{menukeys}
\NewEnviron{command}[2]{% 
\par
\reversemarginpar\marginnote{\texttt{\string#1}}
\BODY
\par
\textbf{Example:}
\texttt{\string#1\detokenize{#2}}
\par
#1#2
\par
}%


\begin{document}

\begin{command}{\keys}{{Shift + F5}}
This command allows you to add keyboard strokes.
\end{command}

\begin{command}{\TeX}{}
This command prints the \TeX\ logo.
\end{command}

\begin{command}{\textbf}{{\TeX}}
This command prints its argument in bold.
\end{command}

\begin{command}{\rule}{[-2pt]{1em}{1em}}
This command print a black box.
\end{command}

\end{document}