Re: Two issue with Measure_grouping_engraver

[James Lowe]

Hello,


On 05/08/18 08:38, James Lowe wrote:
> Harm,
>
>
> On 03/08/18 16:03, Thomas Morley wrote:
> > 2018-08-03 16:51 GMT+02:00 James Lowe <address@hidden>:
> > > Hello
> > >
> > >
> > > On 03/08/18 13:32, Thomas Morley wrote:
> > > > Hi,
> > > >
> > > > while playing with the Measure_grouping_engraver
> > > > see:
> > > >
> > > > http://lilypond.1069038.n5.nabble.com/changing-symbols-used-by-Measure-grouping-engraver-td215283.html 
> > > >
> > > > I noticed two things which may qualify as bugs.
> > > >
> > > > (1) A documentation issue
> > > >
> > > > I tried to get MeasureGrouping in default 4/4-time, but nothing 
> > > > happened.
> > > > One has to set beatStructure and baseMoment accordingly. The current
> > > > docs make it sound it should work out of the box, though.
> > > >
> > > > \version "2.19.82"
> > > >
> > > > \new Staff \with { \consists "Measure_grouping_engraver" }
> > > >     {
> > > >         %% to get MeasureGrouping, next two lines need to be 
> > > > uncommented
> > > >       %\set Timing.beatStructure = 4,4
> > > >       %\set Score.baseMoment = #(ly:make-moment 1/8)
> > > >       \repeat unfold 8 a'8
> > > >     }
> > >
> > > Is this just a documentation issue though?
> > >
> > > *should* it work out of the box (to use your phrase) and so 
> > > documentation is
> > > correct and the bug is in the code?
> > >
> > > We don't document bugs after all.
> > >
> > > James
> > Hi James,
> >
> > this is not a bug in the code, afaik.
> >
> > But the functionality of MeasureGrouping relies on appropriate
> > settings for beatStructure and baseMoment.
> > This should be documented, that's all.

I don't know how this cannot be a bug in the code or perhaps I don't 
understand how this should work but giving an example for 4/4 with the 
one example doesn't help anyone either.

For instance in an attempt to edit the existing snippet, I played about 
with different \time settings to see if I could show the differences - 
it's always good to show a negative before showing a positive I find.

Why would using using \time values of 6/8, 5/8, 4/8 engrave something 
(triangles) and 3/8 not?

Playing about with the form

\score {
{
  \time X/Y
  \repeat unfold 16 a'4
}
  \layout {
    \context {
      \Staff
      \consists "Measure_grouping_engraver"
    }
  }
}

Where X and Y change I cannot figure out why I get some engraving with 
some values and not other

I've attached a screenshot of some random output values.

Why do I get something for 4/8 and not 7/8 is it because of the value of 
the note and how we define a group? I cannot work out the logic to it.

So explaining it for 4/4 makes no sense in that there has to be 
something more fundamental in the explanation or it is a bug.

Can you or anyone help?

James

Screenshot_22.png
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