I don't want to speak for Dan, but I believe the objective is to get user code moved over to actually using exact rationals rather than moments for these properties, not just to allow the use of exact rationals in addition to moments.
It's worth pointing out that there were extended discussions on the devel list regarding the design of this patch series prior to it being merged. On Sat, Feb 8, 2025 at 1:45 PM Valentin Petzel <valen...@petzel.at> wrote: > Hello Paolo, > > > Why has forward compatibility not been ensured for this function? > > The relevant merge request is this one: > > https://gitlab.com/lilypond/lilypond/-/merge_requests/2546 > > As you can see this one also introduces a compatibilty property > `proportionalNotationDurationAsMoment` and a convertly rule that replaces > `proportionalNotationDuration` by `proportionalNotationDurationAsMoment`. > > That being said, I’m not sure if this is actually a good design? After all > it > is not really a compatibity feature, as it only exists after the change, > and > essentially it could be replaced by converting > > `proportionalNotationDuration = ...` > > to > > `proportionalNotationDuration = #(ly:moment-main #{ ... #})` > > or something. Instead this introduces a new deprecated property, which to > me > seems quite weird. > > Cheers, > Valentin
