Re: \parenthesize and optional arguments

[Marc Hohl]

Am 04.07.2015 um 10:08 schrieb David Kastrup:
[...]
> Well, I'm not enthusiastic about both code and interface.  The problem
> with the code is that
>
> { c'8-\parenthesize-1 [ f'8] }
>
> will no longer compile.

Ah, I see.

>  The first reason for that is that one-paren
> parenthesize will not work for any articulation and/or post-event.  You
> really should try to turn this into tweaks rather than an override.
> Otherwise it will be impossible anyway to parenthesize more than one
> thing differently at one time step.
>
> And of course the second reason is that -1 is no longer interpreted as a
> fingering here but rather as a direction indicator.  Which changes the
> entire meaning.

Of course.

So I discarded the "optional argument" idea and went for \lparenthesize 
and \rparenthesize in combination with tweak.

Now I got

\version "2.19.20"

lparenthesize =
#(define-music-function (arg) (ly:music?)
   (_i "Tag @var{arg} to be left parenthesized.)
   (if (memq 'event-chord (ly:music-property arg 'types))
       ;; arg is an EventChord -> set the parenthesize property
       ;; on all child notes and rests
       (for-each
        (lambda (ev)
          (if (or (memq 'note-event (ly:music-property ev 'types))
                  (memq 'rest-event (ly:music-property ev 'types)))
              (set! (ly:music-property ev 'parenthesize) #t)))
        (ly:music-property arg 'elements))
       ;; No chord, simply set property for this expression:
       (set! (ly:music-property arg 'parenthesize) #t))

    #{ \tweak ParenthesesItem.stencils #(lambda (grob)
          (let ((par-list (parentheses-item::calc-parenthesis-stencils 
grob)))
          (list (car par-list) point-stencil))) #arg #})


{ \parenthesize c }

which results in an error message that I don't understand:

Lilypond parenthesize.ly
GNU LilyPond 2.19.23
»parenthesize.ly« wird verarbeitet
Analysieren...
parenthesize.ly:4:2: Fehler: GUILE signalisierte einen Fehler für den 
hier beginnenden Ausdruck
#
 (define-music-function (arg) (ly:music?)
parenthesize.ly:23:5: illegal character in escape sequence: #\p
parenthesize.ly:4:2: Fehler: syntax error, unexpected EVENT_IDENTIFIER
#
 (define-music-function (arg) (ly:music?)
parenthesize.ly:23:4: Fehler: EOF innerhalb einer Zeichenkette gefunden
{ \
   parenthesize c }
schwerer Fehler: gescheiterte Dateien: "parenthesize.ly"

I remember getting such error messages in combination with some 
unbalanced parentheses, but my editor tells me that this is not the case 
here :-(

Marc

>