Re: Several thoughts for implementing accordion standard bass support

[David Kastrup]

Han-Wen Nienhuys <address@hidden> writes:

> On Tue, Jan 19, 2010 at 11:55 AM, David Kastrup <address@hidden> wrote:
>
>>>> StdbassEngraver = #`((listeners
>>>>                       (note-event .
>>>>                        ,(lambda (engraver event)
>>>>                          (let* ((pitch (ly:event-property event 'pitch)))
>>>>                           (ly:event-set-property! event 'pitch
>>>
>>> This looks wrong - engravers should not modify their inputs. Rather,
>>> the engraver should create the Grob that you are interested in, or it
>>> should acknowledge the grob created by another engraver.
>>
>> Obviously, I have no clue whatsoever about what I am doing, and this is
>> the "poke with a stick until it works(TM)" approach.
>>
>> Could you give a code example or outline for either of the possibilities
>> that you outlined?
>
> I am completely unsure what you are trying to achieve.  Are you really
> trying to typeset noteheads on a staff, or is it something else?

I am trying to do exactly what the posted code _does_ right now.  It
works (maps notes to different octaves than entered, in particular
mapping chord notes to the -1 octave ignoring inversions).  At a future
point of time, the criteria might get more intricate and I may want to
analyze the resulting chords.  But that is reasonably straightforward to
do.

So right now, I just want to do what the code already does.  You are
saying that it does this in a wrong way.  So I am interested in the
right way.  One that does not work just by luck and won't fall apart
into pieces in more complex situations.

Thanks,

-- 
David Kastrup