Feature request: boolean inverting flag

[kalekje]

The default option allows for naked as keys which show a value as true, wonderful. I'm wondering if it's possible to allow in the opts, a way to flag setting naked as false within the key. I would propose the following:

luakeys.parse('bold, !color', {invert_flag='!'}) -> bold=true, color=false

Allowing the user to specify a prefix for a naked that sets it to false. I could see users using *-~! as potential choices, maybe a table of choices could be passed as an alternative, or string with multiple characters for options.

As more high level concept, I wonder about the idea of 'embellishments' where the existence of the flag could be used to modify the key and value to a user's custom function.

The xparse package has these so-called embellishments; https://mirror.its.dal.ca/ctan/macros/latex/contrib/l3packages/xparse.pdf

[Josef-Friedrich]

Thank you for your very clear proposal. I must admit that I have never come into contact with embellishments.

[kalekje]

I definitely think it's an interesting option and a few people would utilize it (I know I would). I tried to replicate the proposed behavior with some hooks and made a preliminary solution for myself, although I view it as inefficient and possibly error-prone.

luakeys = require 'luakeys'

function toggle_bool(t)
  for k, v in pairs(t) do
    if (type(k) == 'string') and k:find('!') then
      t[k:sub(2)] = not v
      t[k] = nil
    end
  end
end

t = luakeys.parse('bold,!color', { hooks = { result = toggle_bool } })

for k, v in pairs(t) do
  print(k, v)
end

yields:

color	false
bold  	true

[Josef-Friedrich]

In the commit ebd2eac I accidentally wrote the option wrong: invert_flat instead of invert_flag. c0f8ed7 fixes this typo.

[Josef-Friedrich]

Can you think of a code example for an embellishment you describe?

[kalekje]

I kind of have a half-baked concept of it being a higher-level approach to the boolean inverting. But here's a more detailed example.

If a parser picks up an embellishment, it would go to a hook and modify the key and val and pass the embellishment to the func.

function parskip_embel(key, val, emb)
  -- key = parskip here, without the emb
  if emb == '*' then
    tex.print('\\setlength{\\parskip}{16pt}')
  elseif emb == '+' then
    tex.print('\\setlength{\\parskip}{12pt}')
  end
  -- etc.  let '-' make even smaller skip, etc
  return key, val
end

luakeys.parse('+parskip', {
  defs = { key = { parskip = { embellishment = parskip_embel } } },
})

Perhaps a better approach would be 'parskip=big'|'parskip=small|etc.' and I'm proposing something too cute.

I have a personal package similar to sparklines. In my key-val opts, I have options like [xaxis] or [*xaxis], where the * puts the x-axis of a graph over top of the plot line, if not, the line is underneath. Similar to this, I can do [*xline=3.5] or without the star. It's really not that hard to just define two keys in some instances,nl which is what I do currently.

[Josef-Friedrich]

What do you think of this suggestion?

luakeys.parse('+parskip', {
  defs = {
    key = {
      parskip = {
        embellishments = {
          ['*'] = function(key, val)
            tex.print('\\setlength{\\parskip}{16pt}')
          end,

          ['+'] = function(key, val)
            tex.print('\\setlength{\\parskip}{12pt}')
          end,
        },
      },
    },
  },
})

[Josef-Friedrich]

Maybe it is enough to specify the embellishments globally under opts, not under defs per the single key definitions?

luakeys.parse('+parskip', {
  embellishments = {
    ['*'] = function(key, value)
      tex.print('\\setlength{\\parskip}{16pt}')
    end,

    ['+'] = function(key, val)
      tex.print('\\setlength{\\parskip}{12pt}')
    end,
  },
})

[kalekje]

I think having either options is important, rather than just globally. For example, let's say you wanted to have a few paragraphs in a box and wanted to control the border thickness, borders, and parskip.

+border=tblr,+parskip

Could make a thick box around a paragraph with big spacing. - could be used for thin box or small skip.

Having it globally though, is nice IMO because it's a conceptually way to create the boolean inverting flag, that may clean up the code.

[kalekje]

Just curious if any additional thought or efforts have been put into this?

Thank you!

[Josef-Friedrich]

Unfortunately I haven't gotten to it yet. Many other projects have distracted me from it, for example this one: https://github.com/Josef-Friedrich/LuaTeX_Lua-API

Wouldn't you be interested in contributing this feature?
I would be very happy about a pull request. Or do you want to become a co-maintainer? Many ideas came from you and you reported many bugs ... Thanks a lot for this

[kalekje]

That seems like a very useful project, nice!

I certainly would be interested in trying. I'm currently working on a Master's thesis so it may take some time, but I'll let you know once I can become more acquainted. I do have some other ideas.