[talk] completing output-file and output-suffix work - was Re: Question re looking up settings in current \midi block.

[Ian Hulin]

OK,

I've been able to do a bit more digging around since I got home and
found David's fix for Issue 2343 and related Rietveld
https://codereview.appspot.com/5698050/

Most of the patch was a nice new procedure paper-variable in
scm/lily-library.scm for getting and setting variables within a \paper
block, looking in any relevant \book (and by implication \bookpart or
top-level declaration.
========================================
(define-public paper-variable
 (let
    ((get-papers
      (lambda (parser book)
        (append (if (and book (ly:output-def? (ly:book-paper book)))
                     (list (ly:book-paper book))
                     '())
                 (ly:parser-lookup parser '$papers)
                 (list (ly:parser-lookup parser '$defaultpaper))))))
  (make-procedure-with-setter
    (lambda (parser book symbol)
      (any (lambda (p) (ly:output-def-lookup p symbol #f))
            (get-papers parser book)))
    (lambda (parser book symbol value)
      (ly:output-def-set-variable!
       (car (get-papers parser book))
       symbol value)))))
===========================================

Most of the rest of the patch was concerned with moving lookups from
parser global variables to using the paper-variable procedure to look
things up in the \paper block.

My question is: can we get away with an equivalent midi-variable
procedure, or do we need this *and* to extend the book object in C++
to add a midi_ property, all the attendant methods as per the paper_
methods, and also an ly:book-midi scheme-callable procedure, so
midi-variable would look something like

(define-public midi-variable
 (let
    ((get-midis
      (lambda (parser book)
        (append (if (and book (ly:output-def? (ly:book-midi book)))
                     (list (ly:book-midi book))
                     '())
                 (ly:parser-lookup parser '$midis)
                 (list (ly:parser-lookup parser '$defaultmidi))))))
  (make-procedure-with-setter
    (lambda (parser book symbol)
      (any (lambda (p) (ly:output-def-lookup p symbol #f))
            (get-midis parser book)))
    (lambda (parser book symbol value)
      (ly:output-def-set-variable!
       (car (get-midis parser book))
       symbol value)))))

This would require changes in lily/book.cc and lily/book-scheme.cc.

What do you think?  Or is there a simpler solution?

I think this is where I backed off from implementing the block
variables before and added the \bookOutputName and \bookOuputSuffix
commands instead.

Cheers,

Ian


On 26/12/12 15:53, Ian Hulin wrote:
> First of all, a very Merry Christmas to you all.
> 
> Unfortunately I've had to spend the holidays in hospital, but I'm
> now a much happier bunny now I have my notebook and have sorted out
> a mobile broadband link.
> 
> I'm trying to prototype something so we can specify names and/or 
> suffixes for midi files and would like to see if I can add
> property checks for things in the \midi block like
> 
> \midi { filename = "Coronation-Anthem" file-suffix =
> "Zadok-the-Priest"} }
> 
> I know ly:output-def-lookup is my friend, but how do I get hold of
> the currently active midi block so I can look up the property?
> 
> Sorry if this seems an obvious question, and I'd probably get the
> answer if I was at home, but I'm out on a limb a bit here.
> 
> Thanks in advance for your help,
> 
> Cheers, Ian Hulin
>