Re: Issue 5621: Improve rehearsal mark position at beginning of staff (issue 547340043 by address@hidden)

[nine . fierce . ballads]

On 2019/12/19 21:39:20, c_sorensen wrote:
> Although I am not an expert in pure/impure calculations, I think that
you are
> misunderstanding this entry in the CG.

I confess, I'm finding it difficult to apprehend this.

> But the rehearsal mark will potentially be placed somewhere different
> depending on the line breaking.

That was already the case when RehearsalMark.self-alignment-X
was fixed to CENTER (and the difference in system height was
more extreme).

If it's a problem now, was it a problem before?  Is this change an
improvement?  If there was/is a problem, can I prove it?  Can I
find a case that triggers circular evaluation?  Can I find a case
where a line break is poorly chosen due to the placement of
rehearsal marks?  I don't know.

Can I play it safe by setting up a pure version of the callback that
returns a constant value like before?  That would be pure, but I
don't understand whether it would be better.

> Of course, this could all be wrong, but it's my best understanding of
how
> pure/impure works.

Thanks for clarifying!  :-D

https://codereview.appspot.com/547340043/