Re: Issue 3917: Add \alternatingTimeSignatures (issue 97110045)

[lilyliska]

This notation _may_ make a score harder to read than typing all meter
changes explicitly.
But the intention of this patch is not to provide a better notation but
to better support an existing notation.


https://codereview.appspot.com/97110045/diff/80001/ly/music-functions-init.ly
File ly/music-functions-init.ly (right):

https://codereview.appspot.com/97110045/diff/80001/ly/music-functions-init.ly#newcode130
ly/music-functions-init.ly:130: alternatingTimeSignatures =
On 2014/05/10 23:50:11, Keith wrote:
> The function does not do what its name implies, alternate time
signatures, so
> you need a long explanation.

> LilyPond has a more understandable way to change the *printed*
time-signature,
> with \override..stencil.  I suggest you make a function to handle just
the part
> that users might find difficult to do themselves:
> fractionList = #(define-scheme-function
>    (parser location timesigs) (list?)
>    (lambda (grob)
>       (grob-interpret-markup grob
>   ...

> \new Staff  \relative c' {
>    \time 6/8
>    \once\override Score.TimeSignature.stencil =
>      \fractionList #'((6 8)(5 8)(1))
>    c8 c c c c c
>    \override Score.TimeSignature.stencil = ##f
>    \time 5/8
>    c8 c c c c
>    \revert Score.TimeSignature.stencil
>    \time 3/4
>   ...

After some consideration I agree that it is better to make the function
a little bit more basic. This leaves the user somewhat more to type, but
also leaves some flexibility to him:

- user can decide which context to override in (e.g. if Timing has been
moved)
- user can decide to make the first actual \time different from the
displayed (although I can't think that's an actual use case)

https://codereview.appspot.com/97110045/diff/80001/ly/music-functions-init.ly#newcode144
ly/music-functions-init.ly:144: #{ \once\override
Staff.TimeSignature.stencil =
On 2014/05/10 23:50:12, Keith wrote:
> On 2014/05/10 22:38:29, uliska wrote:
> > I have the impression that Staff. works just as well?

> Well, if there are many staves, your function changes the initial time
signature
> for the whole score, but prints the special indication only on one
Staff, unless
> the user includes the function in each staff.  (There is a context
called Timing
> for the general case; Timing is usually the same as Score, unless the
user has
> different meter in each Staff.)

That's true and a case I missed to check. So overriding in the Score
context is the correct way.
Of course this is obsolete with the principal change to the function I'm
going to do.

https://codereview.appspot.com/97110045/