Re: Edge cases in TOC hierarchies

[Jean Abou Samra]

Le 07/03/2022 à 23:12, Nate Whetsell a écrit :
> Hi all,
>
> I’m quite new to LilyPond development, so please take this well-salted.
>
> > …I am not sure what the reason was for making \tocItem take a symbol list as 
> > first argument in the first place instead of a mere level of nesting depth as 
> > an integer:
> For what it’s worth, I’m very much in favor of having \tocItem’s first argument 
> be a nesting depth instead of a symbol list.
>
> The only thing I can add is that, in some cases, a (signed) integer 
> representing a relative level may be more useful than an absolute nesting 
> level. Using relative levels, any positive integer would mean the \tocItem 
> would become a child of the previous one, and negative integers would decrease 
> the nesting depth:
>
> \tocItem "foo" % Level 0
> \tocItem 1 "bar" % Level 1, nested in foo
> \tocItem 100 "baz" % Nested in bar
> \tocItem "bla" % Also nested in bar
> \tocItem -1 "spam" % Nested in foo
>
> Where I think this would come in handy is creating a big list of bookmarks by 
> \include-ing several files that all have their own \tocItems. As long as
>
> \tocItem 1 "foo"
>
> put "foo" at level 0 when it’s the first \tocItem encountered, then
>
> \tocItem "oof"
> \include "file.ly" % this file contains \tocItem 1 "foo"
>
> would result in oof at level 0 with foo as a child at level 1, but one could 
> still compile file.ly on its own to get foo at level 0.
>
> (The idea of a relative bookmark level is from LaTeX’s bookmark package: 
> https://ctan.org/pkg/bookmark.)



That is an interesting idea, but unfortunately it makes
it more complicated to add new nesting levels.

\tocItem "score A"

\score { big expression taking 4 screens to scroll ... }

\tocItem "score B"

If I want to refactor A to split the score in two and add
nested TOC entries, I also have to touch B to specify -1
(or -n) as a relative level. Also it means you can't reorder
the scores without editing them if there are different nesting
levels at play. I think something like this would be nice,
but under a different form, say,

myToc = \makeToc
\addToToc \myToc \tocItem "foo"
\addToToc \myToc \tocItem 1 "bar" % level is relative to TOC root
myNestedToc = \makeToc
\addToToc \myToc 1 \myNestedToc % nested myNestedToc at level 1
\addToToc \myNestedToc \tocItem 1 "baz" % relative to myNestedToc root

or something like that. Problematic is that this requires
a refactoring of \tocItem because it currently works via
a side effect and not by adding an object somewhere, so for
example this produces TOC items in the order of \tocItem calls:

\version "2.22.1"

\markuplist \table-of-contents

foo = \tocItem \markup foo
baz = \tocItem \markup baz

{
  \baz
  c'1^"baz"
  \pageBreak
  \foo
  c'1^"foo"
}

So, well, I think it's a great idea but it requires somewhat
more thought than I can afford right now.

Jean