Re: Catch direction operators

[David Kastrup]

Paul Morris <address@hidden> writes:

> David Kastrup wrote
>> Looks fine.  \colorizeDir is not actually being used as a tweak here,
>> but then that makes pretty little sense anyway.
>
> Ok, I've added it here:
> http://lsr.dsi.unimi.it/LSR/Item?id=889
>
> Since it requires 2.17 I had to comment out the whole thing, and add a
> single note to get the LSR to accept it.

Might make more sense to add it to LilyPond's own snippet base, I guess.
Obviously, we have no limitations how new any snippets may be there.

> I also split colorizeDir up into two parts, as shown below.  This seemed
> easier to understand and avoids (re-)defining grob-colorize-dir for every
> grob that gets colored.  Let me know if that's not a good call.

Well, I try keeping the global name space uncluttered, but if you see an
actual potential for use outside of \colorizeDir, that's certainly a
small price to pay.

> #(define (grob-colorize-dir grob)
>    (let ((ev (event-cause grob)))
>      (case (and ev (ly:event-property ev 'direction))
>        ((1) red)
>        ((-1) blue)
>        (else '()))))
>
> colorizeDir =
> #(define-music-function (parser location item)
>    (symbol-list-or-music?)
>    #{ \tweak color #grob-colorize-dir #item #})

-- 
David Kastrup