Set up label in add-toc-item!

[Robert Kubosz]

Hello!

I have a question that bothers me. Can I put a label in a markup 
function/add-toc-item! ? I'll explain:
I have scores, that obviously use a \header {} block. I use a custom 
scoreTitleMarkup, that obviously manages each piece's title markup and 
also calls add-toc-item! that puts an item in toc-items list. I want the 
add-toc-item! to put the piece label also to the 'label-page-table, so 
there would be no need for an extra toplevel "\label 'someSymbol" command.

Below is a snippet that compiles, but it clearly does not work as I want 
it to do. I would be very grateful if somebody would help me with this 
or give proper guidance where to find a solution.


\version "2.19.83"

#(let ((toc-item-list (list)))
     (set! add-toc-item!
           (lambda (label markup-symbol text . rest)
               (set! toc-item-list
                     (cons (append! (list label markup-symbol text) rest)
                           toc-item-list))
            (make-music 'EventChord
               'page-marker #t
               'page-label label
               'elements (list (make-music 'LabelEvent
                                           'page-label label)))))
     (set! toc-items (lambda ()

                         (reverse toc-item-list))))


#(define-markup-command (mymarkupfunction layout props) ()

     (let ((title (chain-assoc-get 'header:piece props))
           ;; (label (gensym "piece"))
           (label 'piece1 ))
         (display (toc-items))
         (display "<-should be empty \n")
         (add-toc-item! label 'tocPieceMarkup title "123") ;;"123" is a 
piece number, take it here as placeholder
         (display (toc-items))
         (display "<-one toc item \n")
         (let ((table (ly:output-def-lookup layout 'label-page-table)))
             (display table)
             (display "<-here should be at least one item, but isn't!\n"))
         (interpret-markup layout props (markup title))))


\paper {
    scoreTitleMarkup = \markup \mymarkupfunction
}


\score {
    \header {
        piece = "foo"
    }
    {c' c' c' c'}
}

\markup { There should be a working page reference \page-ref #'piece1 
"0" "?" }