On 6/23/2023 12:43 PM, Carlos via ntg-context wrote:
On Thu, Jun 22, 2023 at 03:32:25PM +0200, Hans van der Meer via ntg-context
wrote:
\starttext
x \rightarrowfill x
x \leftarrowfill x
hbox to 5cm:
y\hbox to5cm{\rightarrowfill}y
y\hbox to5cm{\leftarrowfill}y
\stoptext
But obviously not in an dimensioned \hbox, whereas Knuth's version does that
too.
On 22 Jun 2023, at 15:11, Hans Hagen via ntg-context <ntg-context@ntg.nl> wrote:
x \rightarrowfill x
x \leftarrowfill x
yours sincerely
dr. Hans van der Meer

I find this interesting. I agree with Hans vdM.
So what would be the acceptable standard given an x length of a glue?
In the above examples, it's all preset.
Is a rule of thumb — no pun intended here — to apply thereafter
a glue, in this case a \vrule that follows the box and precedes the
other glue? that is, the \rightarrowfill or \leftarrowfill?
I mean. Once you get the glues messed up, the whole box crumbles.
I'm not sure how you can mess up glue so that the box is no longer a
box. Boxes remain boxes.
How good would \meaning be here, notwithstanding the valuable info of
the macro it provides, if it can't print out, let alone source it up,
the more accurate dimension, let alone the measurement.
I don't follow. Does this come from ChapGPT?
So, one would need to know the preset layout of the page to have an idea
about it?
Hans H. pulled the old modified trick of 'works here'.
Well, when used in a paragraph it works indeed. No trick involved. But
as it uses a specific mechanism in an hbox you need to trigger that
(unless you want to add overhead that will kake tex crawl).
Like a magician… now all of a sudden evetything works, but unlike TeX's
Not sure what this refers to. Much of TeX is magick but what is bad
about that?
\hbox to 1in{\vrule \rightarrowfill \ 1in \leftarrowfill\vrule}
or
\hbox to 1cm{\vrule \rightarrowfill \ 1cm \leftarrowfill\vrule}
which gives an accurate description, not to mention measurement,
It depends on what you expect. First of all, your assumption that the
arrow fill is the same as in plain tex is wrong.
(1) one can define an arrow fill using a leader that uses some (happen
to be present in tex math fonts) glyphs: repeated minuses followed by
some magic kern and an arrow head.
(2) You can hope that the magick kern is right and that the minus aligns
with the arrows bar.
(3) You also assume that the math font matches the text font.
(4) Normally an arrow fill is something math anyway. Where there can
also be something on top or below, or where it can be a top or bottom
accent.
a
\vbox to 5pt{x\vrule\rightarrowfill \ x \leftarrowfill\vrule\ x}
or
x \rightarrowfill x
x \leftarrowfill x
or
\vbox to 3pt{x\vrule\rightarrowfill \ \leftarrowfill\vrule\ x}
\ \rightarrowfill \
\ \leftarrowfill \
in LMTX doesn't say much
What should it say? You get a space, an arrow and a discarded space.
That said: I think you miss a few points here:
(1) I know Hans vd Meer well and he knows ConTeXt well. He's quite
capable of figuring out how to use advanced features and I bet he likes
the following variant of arrows in text. Next time we meet I'll show him
some more adaptive tricks (although I bet he can figure them out himself).
\starttext
% \setupexternalfigures
% [location={default,global}]
% \startsetups adaptive:test
% \setbox\usedadaptivebox\hbox to \usedadaptivewidth yoffset
-\usedadaptivedepth \bgroup
% \externalfigure
% [cow.pdf]
% [width=\usedadaptivewidth,
% height=\dimexpr\usedadaptiveheight+\usedadaptivedepth\relax]%
% \egroup
% \stopsetups
\startsetups adaptive:test
\setbox\usedadaptivebox\hbox to \usedadaptivewidth yoffset .25ex
\bgroup
\startMPcode
drawarrow ((0,0) -- (\the\usedadaptivewidth,0)) randomized
(ExHeight/2);
\stopMPcode
\egroup
\stopsetups
\dorecurse{5}{
\dostepwiserecurse{1}{150}{1}{%
this~#1.##1 is~#1.##1 test~#1.##1
{\adaptivebox[strut=yes,setups=adaptive:test]{\strut}}
}
\blank
}
\stoptext
(2) If someone wants a plain (or fot that matter latex) solution then
one can use these macro packages or write a macro that mimicks
expectations.
(3) I don't like "Hans H. pulled the old modified trick of 'works
here'." kind of remarks because they have a rather negative undertone
and I don't know how to read that.
Hans
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