enharmonic problem with \transpose - should we modify it?

[Janek Warchoł]

Summary: { \key c \minor  \transpose gis as { es } } produces feses in output. I think it would be better if it outputted es.

I have a piece written in es minor, which contains a lot of sharps and naturals (along with passages of flat notes). I'd like to "transpose it enharmonically" so that sharp notes become flat notes a scale step above, natural notes become double-flatted notes, but regular passages of flat notes aren't affected. \transpose gis as works for this with one exception: it produces ceses and feses everywhere instead of bes and es (which would fit the key signature better). This disturbs the harmonic structure: when a passage like this { \key es \minor as' bes' des'' bes' ges' es' as' as' } is transposed, most flat notes aren't affected (because \transpose doesn't create triple flats), but some are - and intervals change, for example first one changes from major second to diminished third.

I tried using \naturalizeMusic from NR 1.1.2 on it, but this results in problems in other places (because \naturalizeMusic ignores key signature).

I think it would be good to either modify \transpose function, or add a function which is similar to \transpose, so that described results can be acheived.

What do you think?

I searched for transpose in sources and checked all results that were not docs and regtests, but my scheme reading skills are too low: i cannot identify where it is defined (i have an impression that it's definition isn't all in one place). Please give me some pointers.

cheers,

Janek