Re: Getting pitch out of a pair

[Urs Liska]

Am 17.01.2015 um 00:21 schrieb address@hidden:
> On 2015-01-17 00:16, Jay Anderson wrote:
> > On Fri, Jan 16, 2015 at 4:02 PM, address@hidden 
> > <address@hidden> wrote:
> > > I store two pitches in a pair variable
> > > x = #'(b . cis')
> >
> > pitches = #(cons #{ b #} #{ cis' #})
> > #(display (ly:pitch? (car pitches)))  => #t
>
> Ok that works but looks really bad....
> I liked the clean way the #'(b . cis') looks.
>
> Is there some other way of storing two pitches and accessing each one 
> in a music-function?

You can encapsulate the ugliness in one more function:

#(define x #f)

setTransposition =
#(define-void-function (parser location a b)
   (ly:pitch? ly:pitch?)
   (set! x (cons #{ #a #} #{ #b #})))

foo =
#(define-music-function (parser location bar) (ly:music?)
   (define from (car x))
   (define to (cdr x))
   #{
     \transpose $from $to $bar
   #})

{
  \setTransposition a b
  \foo a
}


HTH
Urs
> // Anders