Freeman, On Wed, Dec 23, 2020 at 2:41 PM Freeman Gilmore <freeman.gilm...@gmail.com> wrote:
> > > On Tue, Dec 22, 2020 at 1:02 PM Mark Stephen Mrotek <carsonm...@ca.rr.com> > wrote: > >> Freeman, >> >> >> >> http://lilypond.org/doc/v2.19/Documentation/internals/key_005fengraver >> > > I read through the Key_Engraver, url above, and related KeySignature and > KeyCancellation. > > The only details there, which I think I know, is how the pairs are > constructed in the keyAlterationOrder. And they have it wrong. I > believe it should read: … *step *is a number from 0 to 6 and *alter *from > -2 (*flat*) to 2 (*sharp*)? (Not -2 (*sharp*) to 2 (*flat*).) > > No details are given as to how the alist order is read or constructed. > I do see The 5th in the pairs (step). I know that the alist cannot be > read with assoc, at least in its simple form. > > Any suggestions were the details of the keyAlterationOrderis explained? > That's the best documentation we have. The next place to look is in the source. Line 177 of ly/engraver-init.ly is where keyAlterationOrder is defined: https://gitlab.com/lilypond/lilypond/-/blob/master/ly/engraver-init.ly keyAlterationOrder = #`( (6 . ,FLAT) (2 . ,FLAT) (5 . ,FLAT ) (1 . ,FLAT) (4 . ,FLAT) (0 . ,FLAT) (3 . ,FLAT) (3 . ,SHARP) (0 . ,SHARP) (4 . ,SHARP) (1 . ,SHARP) (5 . ,SHARP) (2 . ,SHARP) (6 . ,SHARP) (6 . ,DOUBLE-FLAT) (2 . ,DOUBLE-FLAT) (5 . ,DOUBLE-FLAT ) (1 . ,DOUBLE-FLAT) (4 . ,DOUBLE-FLAT) (0 . ,DOUBLE-FLAT) (3 . ,DOUBLE-FLAT) (3 . ,DOUBLE-SHARP) (0 . ,DOUBLE-SHARP) (4 . ,DOUBLE-SHARP) (1 . ,DOUBLE-SHARP) (5 . ,DOUBLE-SHARP) (2 . ,DOUBLE-SHARP) (6 . ,DOUBLE-SHARP) ) It appears that the accidentals show up in the list in the relative order they will appear in a key signature. They are grouped by the kind of alteration (flats, sharps, double flats, double sharps). So for sharps, the first to appear in a key signature is f#, followed by c#, followed by g#, then d#, and so on. For flats, we start with bb, then eb, then ab, and so on. I don't know what other documentation you want. I hope this helps. Carl
