Why aren't my keywords recognized when immediately followed by a comma?

Question

I am using listings to display custom keywords in bold. In my listings, those keywords are sometimes followed by a comma. However, in the example below, any comma following a keyword will prevent the keyword from being recognized.

Rendering of the code below

How can I make listings recognize CustomKeyword and if as keywords, even when they're immdiately followed by a comma ?

\usepackage{lstlistings}

\lstdefinelanguage{csharp}{
  alsoletter={@,=,>,},
  morekeywords={return, if, is, int, CustomKeyword, else, or, bool},
  sensitive=true,
  morecomment=[l]{//},
  morecomment=[s]{/*}{*/},
  morestring=[b]"
}

\lstset{
  language=csharp,
  showstringspaces=false,
  columns=spaceflexible,%fullflexible,
  mathescape=true,
  numbers=none,
  numberstyle=\tiny,
  basicstyle=\codestyle
} 

\begin{lstlisting}[columns=fullflexible]
CustomKeyword  // OK in bold.
CustomKeyword, // Not in bold anymore.
if //OK in bold
if, // Not in bold anymore
\end{lstlisting}

I'm sure you mean "comma", but just in case you really did want your code to have a "coma", we have answers for that at http://tex.stackexchange.com/questions/122116/how-to-prolong-compilation-time-while-engaging-in-leisure-activities. I am just having fun, of course. Welcome to the site. — Steven B. Segletes, Jan 22 '15 at 14:48
Please turn your code into a minimal working example (MWE). Write alsoletter=@=>, instead of alsoletter={@,=,>,},; the latter defines , as a "letter", which means that listings treats it as a valid character in identifiers and keywords. — jub0bs, Jan 22 '15 at 14:48
Thank you for pointing this out @StevenB.Segletes now corrected — Mikaël Mayer, Jan 22 '15 at 14:51
Corrected spelling will help for future searches of the topic. — Steven B. Segletes, Jan 22 '15 at 14:51
@Jubobs your solution works. Please post it so that it will help people looking for the same answer. — Mikaël Mayer, Jan 22 '15 at 14:53

jub0bs · Accepted Answer · 2015-01-22T17:04:23.123

The problematic line is

alsoletter={@,=,>,},

You shouldn't use commas to delimit the characters you want to declare as "letters". If you do, listings takes those commas literally and declares the comma itself as a "letter"; as a result, listings treats if, as an identifier distinct from if.

Correct alsoletter syntaxes include

alsoletter={@=>},

and even (much less readable!)

alsoletter=@=>,

(Note that the comma at the end of that line is simply interpreted as a delimiter for listings key-value pairs, not as a character declared as "letter".)

enter image description here

\documentclass{article}

\usepackage{listings}

\lstdefinelanguage{csharp}{
  alsoletter={@=>},
  morekeywords={return, if, is, int, CustomKeyword, else, or, bool},
  sensitive=true,
  morecomment=[l]{//},
  morecomment=[s]{/*}{*/},
  morestring=[b]",
}

\lstset{
  language=csharp,
  showstringspaces=false,
  columns=spaceflexible,%fullflexible,
  mathescape=true,
  numbers=none,
  numberstyle=\tiny,
} 

\begin{document}
\begin{lstlisting}[columns=fullflexible]
CustomKeyword  // OK in bold.
CustomKeyword, // in bold too :)
if //OK in bold
if, // in bold too
\end{lstlisting}
\end{document}

Why aren't my keywords recognized when immediately followed by a comma?

1 Answers1

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