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

[k-ohara5a5a]

The score is harder to understand with this function, than it was after
I expanded the function's contents in-line.  The boundary of the action
of this function (part timing, mostly printed representation) is hard to
understand and remember.

This version of the function does partial changes to the internal
timing, and part to the printed indication.  The built-in functions
described in the manual up to this point make consistent changes to
*both* LilyPond's counting of measures and to the printed time
signature.


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 =
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
 ...

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 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.)

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