Re: moving tweaks into markup-definition

[David Nalesnik]

Hi Orm,

On Wed, Sep 17, 2014 at 7:57 AM, Orm Finnendahl <address@hidden> wrote:

Am Mittwoch, den 17. September 2014 um 07:53:48 Uhr (+0100) schrieb James:
> Do you have any other suggestions we could improve the documentation
> with perhaps?

The main problem in this special case for me is the fact, that David's
code suggests that the first three elements of the prop argument of a
define-markup-command are alists which contain mutable properties,
immutable properties and font-defaults (in that order).

Yes, you unknowingly corrected me!  Mutable, immutable, font-defaults is the correct order.

 

In addition, I don't know:

1. Which properties of layout objects are mutable/immutable?

Immutable properties are stored for all grobs in the variable 'all-grob-descriptions' in the file scm/define-grobs.scm.  You can obtain them for a specific type of grob with the function ly:grob-basic-properties, which takes a grob as argument. 

Immutable properties are common to all grobs of a particular type, so you'll see many properties set to procedures.   

Mutable properties hold the results of applying those functions to individual grobs.  You can read them for a grob with ly:grob-properties.

An override adds a (property . value) pair to the head of the _immutable_ properties alist.  (So, of course, that's exactly what I was doing in the function earlier in the thread.  The procedure acons would be what I would have liked to use, since overrides add a new pair, leaving the older setting of the property intact in the tail of the list--but I couldn't manage to reset the variable that way.  Don't understand why.)

2. Although David's set! instruction to reassign the props symbol
   makes that improbable: Could there be other elems at the end of the
   prop list (and which, if there are)?

I'm not sure I follow.

If you do this to the function above, you get a result of #t.  (I'm including the whole with the variable naming fixed.)

\version "2.19.5"

#(define-markup-command (secs layout props numsecs)

   (string?)

   (let* ((mutable (car props))

          (immutable (cadr props))

          (font-defaults (caddr props)))

     

     (display (equal? props (list mutable immutable font-defaults)))

    

     (set! immutable (assoc-set! immutable 'self-alignment-X -0.5))

     (set! immutable (assoc-set! immutable 'padding 4))

     (set! props (list mutable immutable font-defaults))

     

     (interpret-markup layout props

       (markup

        #:fontsize -1

        #:bold numsecs))))

%%%%%%%%%

Hope this is helpful.

--David