Re: proposed Patch: \define-scheme-function

[Carl Sorensen]

On 9/7/11 11:20 AM, "David Kastrup" <address@hidden> wrote:

> 
> 
> The recent \contextStringTunings fixes were dissatisfactory to me
> because I found the user interface awkward anyway.
> 
> Employing <URL:http://codereview.appspot.com/4969062>, one can code a
> new command and the respective regtest as follows:
> 
> %% A scheme function for converting a chord to a string tuning
> stringTuning =
> #(define-scheme-function (parser location chord) (ly:music?)
>   (let* ((ev-chord (car (extract-named-music chord 'EventChord))))
>    (reverse (event-chord-pitches ev-chord))))
> 
> \header {
> 
>   texidoc = "For other tunings, it is sufficient to set
>     @code{stringTunings}. The number of staff lines is adjusted
>     accordingly."
> 
> }
> 
> \new TabStaff {
>   \set TabStaff.stringTunings = \stringTuning <f' ais' dis'' gis''>
> 
>   \relative c''  { c4 d e f }
> }
> 
> 
> This is more obvious and nicer as either using #`(,(ly:make-pitch ...) ...)
> (and, by the way, I have never seen such a strange tuning, so I consider
> it likely that the respective arguments were simply wrong) or
> contextStringTunings.

Yes, this is much better.  And it can also replace \makeStringTuning, I
believe.

%% A scheme function for converting a chord to a string tuning
stringTuning =
#(define-scheme-function (parser location chord) (ly:music?)
  (let* ((ev-chord (car (extract-named-music chord 'EventChord))))
   (reverse (event-chord-pitches ev-chord))))

\header {

  texidoc = "For other tunings, it is sufficient to set
    @code{stringTunings}. The number of staff lines is adjusted
    accordingly."

}

customTuning = \stringTuning <f ais dis' gis'>

myNotes = { c4\4 e\3 g c }

<<
  \new FretBoards \with { stringTunings = \customTuning } {
      \chordmode {c1}
   }
  \new Staff {
    \relative c' {
      \myNotes
    }
  }
  \new TabStaff \with { stringTunings = \customTuning } {
    \relative c' {
      \myNotes
    }
  }
>>


And I think it possible that judicious use of this capability could greatly
simplify the creation of predefined fretboards, although I haven't yet
looked into it carefully.

Thanks for making this, David. I really like it.


Carl