Re: issues with "afterGrace" since 2.20

[Lukas-Fabian Moser]

> > 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 .

But is it really desirable to make it easy to use afterGrace factors >= 
1? (We warn about them, but only if the factor is > 1. To be honest, I'm 
wary about the factor = 1 case...)

Obviously it's impossible to allow both i) the OP's syntax (use a naked 
duration as main note) _and_ ii) durations as afterGrace offsets.

At the moment we have neither. But one of them should be possible:

For i), limit afterGraceFractions to proper fractions (< 1)
For ii), distinguish factors from durations (offsets) by being < 1 or 
integers >= 1. (In the latter case, warn if the length of the duration 
exceeds the length of the main note.)

Lukas