key-valuelistings
I try to create the arguments for a package which uses keyval, with macro, but this does not work:
Here is the demo code:
\documentclass{minimal}
\usepackage{listings}
\lstset{language=Pascal}
\def\flags{language=Pascal}
\lstset{\flags}
\begin{document}
\end{document}
The first \lstset works. The second fails with
! Package keyval Error: language=Pascal undefined.
Any ideas on how I can do this?
The \c@lstlisting macro is the lstlisting counter. You could try \makeatletter\let\c@lstlisting\@undefined\makeatother short before the line where the error appears to official declare the macro undefined. Also often a \relax is used instead of \@undefined.
In the world of listings, there are mainly three kinds of characters: letter, digit, and other. (It is not pronounce or adjective, but a class named o-t-h-e-r literally.) The manual says that all keywords (should) consist of a letter followed by alpha-numeric characters. That is to say that ab, a2 are good keywords and that 12, 1b, 1?, a?, !b, !2, and !? are not keywords.
So, what makes others so special? An answer is that others are used to separate tokens. In your example, we recognize print as a method/function because it is separated by ./:: and (). Otherwise if . and : were letters we can only see two tokens, namely my_class.print() and my_class::print.
In this example, only the second bar is bold because listings sets alsoletter={.}, for [5.0]Lua.
\begin{lstlisting}[language={[5.0]Lua},morekeywords={bar}]
foo.bar
foo:bar
\end{lstlisting}
But sometimes we really need to color such symbols. So listings allows one to write otherkeywords={=>}. Notice that the second bar is still bold --- because listings still regards = as other.
\begin{lstlisting}[language={Haskell},morekeywords={bar}]
foo=>bar
foo<=bar
\end{lstlisting}
But otherkeywords does not support class number. In your example,
classoffset=2, keywordstyle=\hakuna, morekeywords={matata},
is equivalent to keywordstyle=[2]\hakuna, meaning applying \hakuna for all second class keyword, and morekeywords=[2]{matata}, meaning adding matata as a second class keyword.
However, as in your question 1, there is no otherkeywords=[2] syntax.
For question 2 it is hard to tell why it works. The remaining is my guess: writing morekeywords=[3]{Aal::Izz.Well} will make listings add Aal::Izz.Well as a third class key word. But listings will not see this keyword when parsing your code because, as I explained, others separates tokens. However, otherkeywords={Aal::Izz.Well} forces listings take a look, after it reads Aal, at : and do further checks.
You may try something like:
\lstnewenvironment{print}{%
\lstset{style=PRETTYPRINT}
\tracingmacros1
\lstset{morekeywords=[1]{Aal::Izz.Well}}
\tracingmacros0
\lstset{otherkeywords={Aal::Izz.Well}}
}{}
and found that even otherkeywords add the keyword to the first class. The latter appear to be in the third class. (guess why~~)
Best Answer
The
keyvalapproaches all avoid expanding input, so in your\lstset{\flags}example the code sees\flagsand not the content of the macro. The error message here is a bit unhelpful as it is expanded by TeX, so it looks like what you expect! You need to expand the input before applying the keyval macro(I assume the real problem has this wrapped up inside a macro or similar, where you can do the appropriate expansion.)