Setting the value of a music property

[Joseph Wakeling]

Dear everyone,

A possibly dumb question -- I'm having some difficulty working out how
to set the value of a given music property.

Here's a little piece of Lilypond Scheme adapted from the
naturalizeMusic.ly snippet:

    naturalizeMusic =
    #(define-music-function (parser location m)
       (ly:music?)
       (naturalize m (ly:music-property music 'naturalize-style)))

Now, naturalize-style I've defined in scm/define-music-properties.scm:

--------------------------------------------------------------------------
diff --git a/scm/define-music-properties.scm
b/scm/define-music-properties.scm
index 2af8f92..6709154 100644
--- a/scm/define-music-properties.scm
+++ b/scm/define-music-properties.scm
@@ -106,6 +106,7 @@ whether to allow, forbid or force a line break.")
      (metronome-count ,number? "How many beats in a minute?")

      (name ,symbol? "Name of this music object.")
+     (naturalize-style ,list? "The rules for what pitch-alterations are
permissible.")
      (no-continuation ,boolean? "If set, disallow continuation lines.")
      (numerator ,integer? "Numerator of a time signature.")
--------------------------------------------------------------------------

... but when I try some Lilypond code along the following lines,

> music = \relative c' { c4 d e g }
> 
> \score {
>   \new Staff {
>     \set Staff.extraNatural = ##f
>     \withMusicProperty #'naturalize-style #(list (cons >= 1) (cons <= -1) 
> (cons >= SHARP) (cons <= FLAT))
>     \naturalizeMusic \transpose c ais { \music }
>   }
>   \layout { }
> }

... I get an error:

> Parsing...code/lily/out/share/lilypond/current/scm/naturalize.scm:10:33: In 
> procedure list-ref in expression (list-ref pitch-limits 0):
> code/lily/out/share/lilypond/current/scm/naturalize.scm:10:33: Argument 2 out 
> of range: 0

... which suggests that 'naturalize-style is being taken as empty by the
ly:music-property function.  Giving it a default value equal to an
actual list,

> naturalizeMusic =
> #(define-music-function (parser location m)
>    (ly:music?)
>    (naturalize m (ly:music-property music 'naturalize-style (list (cons >= 1) 
> (cons <= -1) (cons >= SHARP) (cons <= FLAT)))))

... means it parses without error, so it looks like the
ly:music-property function is currently just using the default value
given, and does not appreciate the 'naturalize-style property as already
having a set value.

So, the question comes down to, what am I doing wrong in trying to set
the 'naturalize-style property of the music?  Putting brackets {} round
the music to which the \withMusicProperty statement should apply doesn't
help.

I tried more directly using the ly:music-set-property! function, but
could not work it out. :-(

Can anyone advise?

Thanks & best wishes,

    -- Joe


P.S. naturalize.scm is not really relevant to this question (I think),
but just in case, I've attached it.

naturalize.scm
Description: Text document