Re: modular "markup" and arguments

[Bric]

On 11/05/2013 07:51 PM, David Kastrup wrote:
> Bric <address@hidden> writes:
>
> > On 11/05/2013 03:08 PM, David Kastrup wrote:
> > > Paul Morris <address@hidden> writes:
> > >
> > > > But I think what you really want is a music function:
> > > >
> > > > \version "2.17.29"
> > > >
> > > > boo =
> > > > #(define-music-function
> > > >        (parser location the-music)
> > > >        (ly:music?)
> > > >      #{
> > > >        \override NoteHead.color = #red
> > > >        #the-music
> > > >        \revert NoteHead.color
> > > >      #})
> > > >
> > > > \relative c' { c4 d e f \boo { g a b } c d e }
> > > For such fixed override/revert pairings you should write
> > > \temporary\override in the music function instead of just \override:
> > > otherwise any previous \override NoteHead.color = #blue will get
> > > overwritten and not get restored afterwards.
> > You rock!  This forum rocks!  Lilypond rocks!
> >
> > That said:  how do I parametrize \boo ?
> >
> > With the color as parameter, for example, for something like:
> >
> >   c4 d e f \boo #'red  { g a b } c d e f8 g \boo #'blue { b d a4 d }
> > dis e fis
> >
> > I realize I'm completely clueless about the syntax
> boo =
> #(define-music-function
>        (parser location color the-music)
>        (color? ly:music?)
>      #{
>        \temporary \override NoteHead.color = #color
>        #the-music
>        \revert NoteHead.color
>      #})
>
> But colors are not symbols but triplets.  The default colors
> red/blue/black... are stored in variables of that name.  So you'd have
> to write
>
> \boo #red { g a b } ...
>
> rather than \boo #'red ...

This is so awesome!

So, can one throw in conditionals?

(1) Can one, for instance, check/manifest the pitch and duration of 
'#the-music'  ?  And based on those values are, write something or not?

(2) And how DOES one write something extra?  For example, add a note, or 
add a \markup (again, conditionally, perhaps).  I tried adding variants 
of the following...

boo =
#(define-music-function
      (parser location color the-music)
      (color? ly:music?)
    #{
      \temporary \override NoteHead.color = #color
      #the-music
      (^\markup "C")
      \revert NoteHead.color
    #})


but none of them work.  Obviously, I don't know where scheme ends and 
lilypond code begins, in the above, and I don't even know scheme that 
well.   (By the way, I think I read the relevant parts of the 
documentation, as much as I could find.  I couldn't find stuff on this 
level)

(3) Is "#the-music" an object, with properties and stuff, and how does 
one access/modify those properties?

thanks.