Re: Direction operators in event-function

[David Kastrup]

David Kastrup <address@hidden> writes:

> Urs Liska <address@hidden> writes:
>
>> But if I simply create two elements in the event-function the explicit
>> direction operator takes no effect:
>>
>> propagate-direction =
>> #(define-event-function (text)(markup?)
>>    #{
>>      -(
>>      -\markup #text
>>    #})
>>
>> {
>>   g'1 ^\propagate-direction "Up" g' )
>> }
>>
>> (here both the slur and the text are printed below the staff.
>>
>> Why is that?
>
> Multiple post events in one post event expression are temporarily
> wrapped in one PostEvents music event.  This is then what gets the
> up/down direction.  When it is unwrapped in use, the direction gets
> lost.
>
> Arguably, dissolving a PostEvents into separate events should try
> applying some fields (tweaks, color, direction?).  Unfortunately, there
> are a lot.  Alternatively, directions and tweaks should bypass
> PostEvents and go through the enclosed events.  Either would have some
> performance impact.  Maybe just walk the property list of a PostEvents
> and copy _everything_ found there?

Tracker issue: 5433 (https://sourceforge.net/p/testlilyissues/issues/5433/)
Rietveld issue: 343440043 (https://codereview.appspot.com/343440043)
Issue description:
  Transfer post-event-wrapper properties when unwrapping  Sometimes
  multiple post-events are wrapped in one PostEvents music event
  temporarily.  When tweaks or direction modifiers or other property
  changes are applied to those, they are now transfered to the
  contained elements when unwrapping in order not to get lost.

-- 
David Kastrup