On Sat, Mar 21, 2015 at 10:06 PM, David Nalesnik <david.nales...@gmail.com>
wrote:
> Hi Abraham,
>
> On Sat, Mar 21, 2015 at 9:13 PM, tisimst <tisimst.lilyp...@gmail.com>
> wrote:
>
>> David,
>>
>>
[...]
> This works perfectly when there are NO rests, but I get this error when
>> there is a rest in the NoteColumn:
>>
>> In procedure ly:grob-array->list in expression (ly:grob-array->list
>> (ly:grob-object grob #)): Wrong type argument in position 1 (expecting
>> Grob_array): ()
>>
>>
>>
> Glad I could help!
>
> If there's a rest, then the note-heads array will be empty. To make this
> work, just add a check that the note-heads list isn't the empty list '().
>
>
Oh, shoot! It's past my bedtime...
The error happens because you're applying ly:grob-array->list to that
grob-array which is empty when there's a rest. So the check has to be
before the conversion to a list:
#(define (flipnotes grob)
(let ((notes (ly:grob-object grob 'note-heads)))
(if (ly:grob-array? notes)
(for-each
(lambda (note)
(let* (;(pitch (ly:event-property (event-cause note) 'pitch))
;; don't need this
(stem (ly:grob-object note 'stem))
(dir (ly:grob-property stem 'direction))
(offset (ly:grob-relative-coordinate note grob X)))
(if (eq? dir DOWN)
(if (and (< offset 0.1) (> offset -0.1))
(ly:grob-set-property! note 'rotation '(180 0 0))
(ly:grob-set-property! note 'rotation '(0 0 0)))
(if (and (< offset 0.1) (> offset -0.1))
(ly:grob-set-property! note 'rotation '(0 0 0))
(ly:grob-set-property! note 'rotation '(180 0 0)))
)
))
(ly:grob-array->list notes))
; alternate return?
)))
--David
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