Re: define-markup-command with variable number of arguments

[Urs Liska]

Am 01.11.19 um 16:01 schrieb Thomas Morley:
> Am Fr., 1. Nov. 2019 um 15:34 Uhr schrieb Karsten Reincke <address@hidden>:
>
> > does anyone has / know about an example of a define-markup-command 
> > implementation
> > using a variable number of arguments / parameters?
> Nope, optional arguments are not possible using define-markup-command.
>
> > Unfortunately, in my system (Linux Ubuntu 19.10 with Lilypond 2.18...) the 
> > normal
> > GUILE / scheme syntax (define (x y . args) ) (doanythingwith args) ) seems to
> > executable.
> >
> > The tutorial LilyPond Extending mentions that there exist such an opportunity
> > (page 19.), but does not contain any example.
> The section of the Extending-tutorial refers to functions, not to the
> define-markup-command which is a macro.
> (At least if I've identified the section you refer to correctly, I
> usually use the big-page-html-version of the docs.)
>
> You could go for properties (see define-markup-commands.scm), but the
> syntax in coding and calling it differs ofcourse and you may encounter
> unwished side-effects (if namings interfer with grob-properties).
>
> For variable amount of args I'd go for list? (or the like) and let the
> body of your code sort it out.


An approach that I personally like very much for its way the input code 
"speaks" is the \with {} clause. You use that by the ly:context-mod? 
predicate and then you can stuff arbitrary key=value pairs in it (and 
parse that within the body, as Harm said).

Urs

> Cheers,
>    Harm