Document Classes ⇒ listings | Line Number Reference in subsequent Call

[you2000too]

Dear all,

After listing a piece of code using listings, I want to use the reference of a line number as the first number of a new listing.

This is a minimal example:

Code: Select all

\documentclass[oldfontcommands, 12pt]{memoir}
\usepackage{listings}         

% Parameters for Python listings
\lstset{
  language=Python,
  basicstyle=\ttfamily,
  numbers=left,
  numberstyle=\tiny,
  numbersep=5pt,
  showstringspaces=false
}

\begin{document}

\begin{lstlisting}[firstnumber=1,escapeinside={@}{@}]
def foo(int x):
 @\label{lst:myListing_2}@doSomething()
 doMore()
\end{lstlisting}

When doSomething is invoked:

\begin{lstlisting}[firstnumber=\ref{lst:myListing_2}]
    doSomething()
\end{lstlisting}

\end{document}

But I got the following errors:

Code: Select all

listingsbasic.tex(32): Error: Misplaced alignment tab character &.
listingsbasic.tex(32): Error: You can't use `macro parameter character #' in vertical mode.
listingsbasic.tex(32): Error: You can't use `macro parameter character #' in horizontal mode.
listingsbasic.tex(32): Error: You can't use `macro parameter character #' in horizontal mode.
listingsbasic.tex(32): Error: Undefined control sequence.
listingsbasic.tex(32): Error: You can't use `macro parameter character #' in horizontal mode.
listingsbasic.tex(32): Error: Missing $ inserted.
listingsbasic.tex(32): Error: Misplaced alignment tab character &.
listingsbasic.tex(32): Error: Undefined control sequence.
listingsbasic.tex(32): Error: Missing $ inserted.
listingsbasic.tex(32): Error: Missing \endgroup inserted.
listingsbasic.tex(32): Underfull \hbox (badness 10000) in paragraph at lines 32--32
listingsbasic.tex(34): Error: Undefined control sequence.
listingsbasic.tex(1): Error: File ended while scanning use of \lst@IfNextChars@@.
listingsbasic.tex(1): Error: Emergency stop.
listingsbasic.tex(1): Error:  ==> Fatal error occurred, no output PDF file produced!

How can this be achieved?

Thank you!

yt.

[cgnieder]

It seems the \ref needs to be expanded first. I haven't hunted down what happens exactly so there are probably easier solutions:

Code: Select all

\documentclass[oldfontcommands, 12pt]{memoir}
\usepackage{listings}

% Parameters for Python listings
\lstset{
  language=Python,
  basicstyle=\ttfamily,
  numbers=left,
  numberstyle=\tiny,
  numbersep=5pt,
  showstringspaces=false,
}

\makeatletter
\def\explstopts@reorder[#1]#2#3{#2{#3}[#1]}
\protected\long\def\explstopts#1#2[#3]{%
  \begingroup
    \let\null\relax
    \xdef\@explstopts{[#3]}%
  \endgroup
  \expandafter\explstopts@reorder\@explstopts{#1}{#2}%
}
\makeatother

\begin{document}

\begin{lstlisting}[firstnumber=1,escapeinside={@}{@}]
def foo(int x):
 @\label{lst:myListing_2}@doSomething()
 doMore()
\end{lstlisting}

\explstopts
\begin{lstlisting}[firstnumber=\ref{lst:myListing_2}]
doSomething()
\end{lstlisting}

\end{document}

This example needs to be compiled twice and produces errors the first time.

If you have other options containing macros you might need to add \noexpand accordingly.

Regards

[jha]

First of all thank you for the solution. Worked almost perfectly.

Unfortunately there is two things that still don't work as I hoped for (mainly due to the fact that I have no clue how TeX really works and what in particular your macro does).

If used with the babel package (ngerman option) it doesn't work any more. bable seems to change the \ref macro, so I could "fix" it by redefining \ref to what it was without babel while using babel. That worked.

Using \explstopt seems to introduce some whitespace and this is where I'm really stuck at. Any help would be really welcome. Thank you in advance.

Here is an example

Code: Select all

\documentclass{scrartcl}

\usepackage{listings}
\usepackage[T1]{fontenc}
\usepackage[utf8]{inputenc}
\usepackage[ngerman]{babel}

\lstset{
  basicstyle=\footnotesize,        % the size of the fonts that are used for the code
  breaklines=true,                 % sets automatic line breaking
  captionpos=b,                    % sets the caption-position to bottom
  numberstyle=\tiny,numbers=left,
  frame=single,                    % adds a frame around the code
  language=Java,                 % the language of the code
  keywordstyle=\bfseries,
}

\makeatletter
\def\explstopts@reorder[#1]#2#3{#2{#3}[#1]}
 \protected\long\def\explstopts#1#2[#3]{%
   \begingroup
     \let\null\relax
     \xdef\@explstopts{[#3]}%
   \endgroup
   \expandafter\explstopts@reorder\@explstopts{#1}{#2}%
 }
\makeatother
% this redefines ref to what it was before it got changed by the babel package. 
% Needed because the above hack assumes to be working with this style of reference resolving 
\makeatletter
\renewcommand{\ref}[1]{\expandafter \@setref \csname r@#1\endcsname \@firstoftwo {#1}}
\makeatother

\begin{document}
\begin{lstlisting}[escapeinside={@}{@}]
  public static void main(String[] args)
  {
    @\label{lst:beforeprint1}@String dataID = args[0];
    System.out.println("some output");
    @\label{lst:afterprint1}@
    
    @\label{lst:print2}@System.out.println("some other code");
  }
\end{lstlisting}
Text that explains stuff (\ref{lst:beforeprint1} to \ref{lst:afterprint1}). In line number \ref{lst:print2} you can see \ldots (whitespace)\explstopts \begin{lstlisting}[firstnumber=\ref{lst:print2}]
  System.out.println("some other code");
\end{lstlisting}
And here there is no extra space:
\begin{lstlisting}[firstnumber=7]
  System.out.println("some other code");
\end{lstlisting}
\end{document}