Re: Writing a function

[Aaron Hill]

On 2019-05-12 3:40 am, David Kastrup wrote:
> Rok Kršmanc <address@hidden> writes:
>
> > Hi!
> >
> > I would like to write a function for the next music expression:
> > \once \override TextScript.extra-offset = #'(0 . 1)
> > c^"o"
> >
> > Here is my try:
> > f =
> > #(define-music-function (parser location offset music)
> >   (number? ly:music?)
> >   #{
> >     \once \override TextScript.extra-offset = #'(0 . $offset)
> >     $music ^"o"
> >   #})
> >
> > When I call this function:
> > \f #1 c
> >
> > I get syntax error:
> > unexpected '^'
> >
> > What am I doing wrong?
>
> First it seems like a bad idea to redefine \f ("forte").  But the main
> problem is that an expression like $music cannot take articulations
> (this has been ameliorated to some degree in current development, 
> likely
> appearing as 2.21 eventually).
>
> You can achieve about the same effect with << $music <>-"o" >> namely
> putting the articulation instead on a simultaneously executing empty
> chord.

Would an event function possibly make more sense?  Consider:

%%%%
\version "2.19.82"

foo = #(define-event-function (offset) (number?)
  #{ \tweak extra-offset #(cons 0 offset)
     ^"foo" #})

{ b'4 \foo #0.5 b' b' \foo #-1 }
%%%%


-- Aaron Hill