when/where/wy is a label for page-ref created?

[Jan-Peter Voigt]

Hello list,

I searched for an explanation in my lilybuntu VM for label creation and 
referencation. There are several .cc files wich reference labels etc. 
But I didn't find the place where they are added and under wich conditions.
I wish to be able to add labels independent of breaks or bar-lines. Do I 
have to create a patch for my lily - and where do I have start with 
that? Or is it just a question of another scheme-script?

If I do a \displayMusic for
{ \bar "" \tocItem \markup { "A" } }
I get:
(make-music
  'SequentialMusic
  'elements
  (list (make-music
          'ContextSpeccedMusic
          'context-type
          'Timing
          'element
          (make-music
            'PropertySet
            'value
            ""
            'symbol
            'whichBar))
        (make-music
          'EventChord
          'elements
          (list (make-music
                  'LabelEvent
                  'page-label
                  'toc54))
          'page-label
          'toc54
          'page-marker
          #t)))

In my footnote-function I added the 'wichbar-part and now I can create 
the label anywhere. But this may lead to unwanted breaks or override an 
exisitng barline. How do I avoid this? Or is there a better solution?

Best regards,
Jan-Peter

On 14.01.2011 14:27, Jan-Peter Voigt wrote:
> Hello List,
>
> I stumbled across a thing with label and page-ref.
> Labels are used to create the table of contents and I use them in my little 
> footnote snippet ( http://lsr.dsi.unimi.it/LSR/Item?id=728 )
> If the label is created on a barline, everything is fine. if it is created 
> somewhere within  a measure, the page is not found anymore. I show this with 
> \tocItem, because its a short snippet:
>
> --snip--
> \markuplines \table-of-contents
>
> \relative c' {
>    \time 4/4
>    \tocItem \markup { "One" } c d % page 1
>    \tocItem \markup { "Two" } e f % page not found
>    \time 3/4
>    \tocItem \markup { "Three" } g a b c % page one
>    \tocItem \markup { "Four" } r2 % page not found
> }
>
> \version "2.13.46"
> --snip--
> I tested it with stable (2.12.3) and unstable (2.13.46) on Linux and Mac.
> In my little snippet I create, like the tocItem command, a label-event in 
> scheme:
> ...
> ;; define label and text before this
> ...
> (make-music 'EventChord 'page-marker #t 'page-label label
>    'elements (list
>      (make-music 'LabelEvent 'page-label label)
>      (make-music 'TextScriptEvent 'direction dir 'text (markup text))
>    )
> )
> ...
> When I later try to fetch the page-number from the lable-table 
> (ly:output-def-lookup layout 'label-page-table), the table does not contain an 
> entry label if it was *not* created on a barline.
> What do you think about this?
>
> I post this to user and devel, so if there is a solution or explanation let me 
> know, if this is a bug discuss it for the bug-tracker.
>
> Regards,
> Jan-Peter
>
>
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