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Date:         Sat, 22 Aug 2015 14:10:58 +0700
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From: Christopher Rowley <c.a.rowley@ICLOUD.COM>
Subject: Re: Help with Expl3-izing some code
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Status: R

Joel

Will has explained well the current status.  I should just add that both the 2e commands and syntax plus 'naughty' non-LaTeX commands will be supported for a long, long time -- well after the new, improved, magic of LaTeX3 goes to grips with this, very subtle and tricky area of mini-page-like structures and llap-like structures in vertical mode.

Note that the major difference between the following 
(I have little idea into which class each falls):

      llap in plain/2e
      Possible versions of llap in (very) expl3
      `\hbox_overlap_left:n etc.

is the presence or absence of \leavevmode, (or its equivalent in Nuspeak ):
 
  as the name suggests this makes a big difference if the structure is used in vmode as it then
  starts a paragraph before adding the box.

Your uses are all within a paragraph or an L-R box where all have much, or maybe exactly, the same effect.

Apologies if my explanation only serves to confuse you more.

Meanwhile, have fun with your typesetting.

Note that the type of structure you are trying to provide: section headings set in the margin, is typographical important.

Thus this will be a standard option in whatever emerges from the higher level design stuff to be built on expl3+++ -- but do not hold your breath as there is a whole heap of difficult 'designing', in many senses of that word, to be done before anything stable emerges.

Best wishes,  chris

Sent from my iPud (\~/)

> On 22 Aug 2015, at 09:59, Will Robertson <wspr81@GMAIL.COM> wrote:
> 
> Hi Joel,
> 
> Always good to see what people are interested in trying out :)
> 
>> On Sat, Aug 22, 2015 at 2:46 AM, Joel C. Salomon <joelcsalomon@gmail.com> wrote:
>> 
>> The commit message at
>> <https://github.com/latex3/latex3/commit/432d3d9> indicates that xbox
>> does not yet have the equivalent of `\parbox`. For the restricted use
>> I’m putting this to (`\parbox[t][0pt]{\somedim}{one or two lines of
>> text}`), can somebody suggest a lightweight alternative? Neither
>> wrapping `\hbox_to_wd:nn` within `\vbox_to_zero:n` nor the other way
>> around worked for me.
> 
> As you've discovered, this is an area that we haven't spent much time
> working on.
> 
> Basically, providing new versions of \parbox and so on requires going
> back to the drawing board and figuring out not just *what* should be
> implemented but the user interface as well -- and we're still a way
> from deciding how parameters for document elements should work.
> 
> For example, you could imagine a CCS-like approach where you can give
> a box an ID or class and then style it from the preamble. The idea of
> a "typeset" module for providing bare-bones elements for typesetting
> might include box support but for your purposes is still some way off.
> The coffins commands might help if you're stacking boxes together, but
> they don't exactly qualify for "lightweight".
> 
> So for the time being I would probably recommend sticking to 2e
> commands... sorry if that's not what you wanted to hear!
> 
> Cheers,
> Will