How to evaluate 'articulations entries?

[Marc Hohl]

Hello list,

I think I have asked a similar question long time ago, but I didn't
find the answer.

Currently, I am working on a little scheme engraver which should read the
'string-number, if given, and should do some calculations, depending on
other articulations, like 'HarmonicEvent.

This is what I got so far:


[snip]

\version "2.15.9"

#(define-public (test_engraver context)
  (let ((string-pitch-list '()) ;; actually not used
        (notes '()))
  `((acknowledgers
      (note-head-interface .
        ,(lambda (trans grob source)
           (set! notes (cons grob notes)))))
    (process-acknowledged
      . ,(lambda (trans)
           (for-each (lambda (note)
             (let* ((event (event-cause note))
                    (pitch (ly:event-property event 'pitch))
                    (art (ly:event-property event 'articulations))
                    ;;(type (ly:music-property art 'string-number)) <- 
this does not work
                    )
                   (display "The event: ")
                    (display "ev")
                    (display " has pitch: ")
                    (display pitch)
                    (display " and articulation: ")
                    (display art)
                    (display " and type: ")
                    (display type)
                   (display " \n")
             )
             ) ;; end lambda (note)
             notes)))
    (stop-translation-timestep
      . ,(lambda (trans) (set! notes '()))))))

\layout {
  \context {
    \Voice
    \consists \test_engraver
  }
}

test = \relative c' {
 c4 d\2 e\2 f g\4 a\4 b\4 < g\4\harmonic >
 c4\3 < d\3 g\2> c\3 r
}
%\displayMusic { \test }
\new Voice { \test }

[snip]

How can I proceed?

Thanks in advance,

Marc