Re: issues with "afterGrace" since 2.20

[David Kastrup]

David Kastrup <dak@gnu.org> writes:

> Lukas-Fabian Moser <lfm@gmx.de> writes:
>
>> meaning: A scale? can be
>> - a fraction?
>> - an non-negative exact rational number
>> - a LilyPond moment whose main part is in turn a scale?.
>>
>> This is fulfilled by 4, hence in your call to \afterGrace 4  { cs16 d },
>> ... 4 is taken to be the afterGrace "fraction" (and in recent
>> versions, there is the warning, added by me, that this fraction is
>> larger than 1)
>> ... { cs16 d } is taken to be the "main" note
>> ... whatever comes after is taken to be the "main" note (since in your
>> minimal example, nothing comes after this, compilation fails
>> completely).
>>
>> I'm not sure about David Kastrup's rationale for allowing a scale? as
>> an afterGraceFraction, but if anybody is aware about the implications
>> his changes might have for LilyPond's syntax, it's him.
>> https://gitlab.com/lilypond/lilypond/-/issues/5327
>> https://gitlab.com/lilypond/lilypond/-/commit/027538606b016afb643555d654cefaee94dfb424
>
> For the optional argument of \afterGrace, there would be some incentive
> in case of a duration to interpret it as a duration rather than as a
> scale factor.  That would, however, make this different from either what
> \afterGraceFraction accepts, or what its name insinuates.  Also it would
> make the predicate scale? be an inadequate description of what the
> argument's type is which would functionally be
> non-duration-scale-or-duration? which of course has the exact same
> implementation.

Correction: a duration (as opposed to a music-length) is _not_ permitted
by scale? but a non-negative exact rational number is (which 4 qualifies
as).

duration-or-scale? would be possible in theory but would create too much
ambiguity for things like 2 .

As in:

> In short, a maze of conflicting considerations in the context of
> creating versatile and uniform behavior leading to a so-so outcome.

-- 
David Kastrup