Re: Altering page numbers

[Kieren MacMillan]

Hi Harm,

> You could go for:
> 
> #(define-markup-command (bookpart-page-number layout props) ()
>    (let ((first-page-number (ly:output-def-lookup layout 'first-page-number))
>          (page-number (chain-assoc-get 'page:page-number props 0)))
>      (interpret-markup layout props
>        (number-format
>          (ly:output-def-lookup layout 'page-number-type)
>          (1+ (- page-number first-page-number))))))

Thanks! I’ll study your solution as part of my Scheme education.  =)

> Though, what about the table-of-content?
> Right now I've not a good idea what should be printed if several
> bookparts have equal page-numbers.

That’s almost more of an editorial choice than a technical one, no? If for some 
reason I want the score for my Opera In Three Acts to have per-act page 
numbers, then I will end up with a TOC that looks something like

  Act One
    Aria 1      I-1
    Aria 2      I-22

Act Two
   Aria 3      II-1
   Aria 4      II-9

etc.

The Dover reprints of Bach works often include per-sub-collection numbering 
alongside the main page numbering, e.g.

    1 [1], 2 [2], … 25 [25], 26 [1], 27 [2], … 124 [99], 125 [1], 126 [2], …

In musical theatre scores, it’s also useful to have double numbering (e.g.,
    page-number-within-entire-score [page-number-within-this-song]

As long as there are switches/parameters/properties that allow the user to 
choose, format, and select/print the various numbers/elements they want — 
including bookpart labels, like the "I" and "II" in my fictional opera example 
— I would consider Lilypond’s job done.

Cheers,
Kieren.
________________________________

Kieren MacMillan, composer
‣ website: www.kierenmacmillan.info
‣ email: address@hidden