Package listings and Perl here documents with apostrophes

Question

I sometimes write ordinary English prose in my here documents in a Perl usage sub, for example

 --[no]alias    [don't] use the alias list in the ini file (default noalias)

The problem is the a single apostrophe seems to disturb the listings package. A short example:

\documentclass[article]{memoir}
\usepackage{listings}
\lstset{language=Perl,stringstyle=\slshape}

\begin{document}
\begin{lstlisting}
my $commentA =   "Please, don't do this";
my $commentB =   "But do this";

print <<HERE;
Please, don't do this
But do this
HERE

my $commentC =   "Please, don't do this";
my $commentD =   "But do this";
\end{lstlisting}
\end{document}

This results (with MiKTEX/TeXstudio) in

Result

The apostrophe in commentA is ignored, while the one in the here document seems to be interpreted as an opening quote.

I have tried to escape the here terminator, but to no avail. Any suggestions (short of avoiding apostrophes in here documents)?

I think How to make a real apostrophe or single-quote in LaTeX is related. — Johannes_B, Oct 21 '14 at 07:17
@Johannes_B I think the question is about the strange formatting one gets in e.g. commentC with the bold "do" after a HERE statement containing an apostrophe, rather than the shape of the apostrophe. — Andrew Swann, Oct 22 '14 at 10:35

score 3 · Accepted Answer · answered Oct 22 '14 at 09:40

3

You can add a morestring for these here statements. With the s option you can have a pair of delimiters, though this is not quite clear in the documentation:

Sample output

\documentclass[article]{memoir}
\usepackage{listings}
\lstset{language=Perl,stringstyle=\slshape}

\begin{document}
\begin{lstlisting}[morestring={[s]{<<HERE;}{HERE}}]
my $commentA =   "Please, don't do this";
my $commentB =   "But do this";

print <<HERE;
Please, don't do this
But do this
HERE

my $commentC =   "Please, don't do this";
my $commentD =   "But do this";
\end{lstlisting}
\end{document}

answered Oct 22 '14 at 09:40

Andrew Swann

95,762

I didn't even notice the bold do. Glad there is a solution. – Johannes_B Oct 22 '14 at 12:48
I have two minor worries. I usually use meaningful here terminators, which requires several morestrings, and in calls to subs with several arguments like mysub (<<HERE, $arg1, $arg2); … HERE the first line is formatted as a string -- unless, of course, I use [morestring={[s]{HERE, $arg1, $arg2);}{HERE}] and then I lose a possible keywordstyle for keywords in the arguments. – Henrik Snog Oct 22 '14 at 18:52
@HenrikSnog Agreed - the solution is going to work best if you keep the keyword and HERE name spaces disjoint. In particular, your HERE name should not be something that could be the argument to a binary shift operator, or you should use a space after << in such a case. – Andrew Swann Oct 23 '14 at 06:37

Package listings and Perl here documents with apostrophes

1 Answers1