How to define macros in order to reuse key-value parameters?

Question

I use the listings package to typeset code in my document. I have defined a new environment via \lstnewenvironment in which I use \lstset to set a large number of options through a list of key-values. It looks like the following:

\lstnewenvironment{mycodebox}[1][]                                                                                                                      
{
  \lstset{
     key1=val1,
     key2=val2,
     % some more options are set
     #1 % so that it can accept more options
  }
}{}   

I use this new environment mostly in two variants where in each variant I need to override some existing (or add new) options. For example:

% variant 1
\begin{mycodebox}[newkey=newval, key1=newval]
 % my code
\end{mycodebox}

and

% variant 2
\begin{mycodebox}[anotherkey=newval, key2=newval]
 % my code
\end{mycodebox}

The two variants share a lot of options but they are different. Can I define two macros/commands like \variant1settings and \variant2settigns that can be used in some way like the following?

\begin{mycodebox}[\variant1settings]
 % my code
\end{mycodebox}

I know that I can use \lstset{options...} to do this before using the environment each time but

1. I don't want the options to run through when I don't specify them before subsequent instances;
2. I want the options to be in the form of a macro (or similar) so that they can be tweaked from one central position.

Answer 1

The expansion of the content of the optional argument #1 has to be postponed, otherwise the macro \optionstocodebox is expanded, letting keyval macros think its content is a complete key name, which isn't, of course.

Using

\begingroup\edef\x{\endgroup\noexpand\lstset{numbers=right,language={C},#1}}\x

will prevent premature expansion and expands it afterwards.

\begingroup...\endgroup is a neat trick to let the redefinition \x be forgotten after it's expanded (which is the case at the end of }}\x.

To be short: the expansion is prevented first for \lstset, then applied afterwards by calling \x.

However, no unexpandable stuff such as \textbf or \textcolor are allowed without fine-tuning. This could be achieved by a brute force \unexpanded{stuff} as a key assignment. The second example \otheroptionstocodebox shows usage with \unexpanded approach.

\documentclass{article}

\usepackage{xcolor}
\usepackage{listings}


\lstnewenvironment{mycodebox}[1][]                                                                                                                      
{
  \begingroup\edef\x{\endgroup\noexpand\lstset{numbers=right,language={C},#1}}\x
}{}   


\begin{document}

\newcommand{\optionstocodebox}{language={Pascal},numbers=left}%



\newcommand{\otheroptionstocodebox}{language={C},numbers=left,stepnumber=3,numberstyle={\unexpanded{\color{red}\tiny}}}%


\begin{mycodebox}[language={C}]
#include<stdio.h>
int main(int argc,char **argv)
{
  printf("Hello World!\n");
}
\end{mycodebox}

\begin{mycodebox}[numbers=left,\optionstocodebox]
program first

BEGIN
WriteLn('Hello World');
END.
\end{mycodebox}


\begin{mycodebox}[language={C},\otheroptionstocodebox]
#include<stdio.h>
int main(int argc,char **argv)
{
  printf("Hello World!\n");
}
\end{mycodebox}


\end{document}

Answer 2

listings allow you to define styles that you can apply to individual listings with style=<stylename>.

\documentclass{article}
\usepackage{listings,xcolor}
\lstdefinestyle{style1}{basicstyle=\ttfamily\color{red}}
\lstdefinestyle{style2}{basicstyle=\scshape\color{blue},frame=single}

\lstnewenvironment{mycodebox}[1][]                                                                                                                      
{
  \lstset{
     basicstyle=\itshape,
     #1
  }
}{}  

\begin{document}
\begin{mycodebox}[style=style1]
This is some text
\end{mycodebox}

\begin{mycodebox}
This is some text
\end{mycodebox}

\begin{mycodebox}[style=style2] 
This is some text
\end{mycodebox}
\end{document}