[NTG-context] new upload

[Hans Hagen <j.hagen@xs4all.nl>]

Hi,

I uploaded a new lmtx (some new - experimental - things will be 
explained after the ctx meeting), but there's one thing that is somewhat 
important.

In addition to the built in units we can now have so called user units. 
There is some more info about this in the lowlevel-registers manual. One 
of the predefined units is 'uu' with an associated \ununit (dimension) 
variable and it's is also interfaced to metafun. That means that when 
you use uu in metapost graphics you have to make sure that you save the 
meaning and/or numeric uu now.

The idea is that just as in mp one can say 20xx with xx being a (sort 
of) unit, one can do the same in tex. Think of

\newdimension \MyUnitA  \MyUnitA 1.23pt

\pushoverloadmode % just in case
     \newuserunit\MyUnitA ua % binds the unit to the variable
\popoverloadmode

x\hskip 10ua\relax x

The units starting with 'u' are considered user units but be carefulk 
with other combinations as we have (and will have more) built into 
context ones, like

pi : pi for Mikael
ft : foot for Alan
fs : (global body) font size
tw : (layout) text width
th : (layout) text height
hs : (current) hsize
vs : (current) vsize
cd : (when set) column distance
cw : (when set) column width
cx : combination cell width
uu : user unit (\METAFUN)

So Mikael can now have

   test \hskip 3pi\relax test

and Alan can have

   \setuplayout
     [width=1ft]

to be consistent with inches.

The reason why we have this mechanism is that it provides a level of 
abstraction. It might evolve over time but don't expect the 600+ units 
possible to show up because one needs sensible shortcuts. Already built 
in unit always win and you cna only bind to already defined quantities.

Here's one for those who want to go beyond the normal:

\newdimension \FooA   \FooA 1.23pt
\newdimen     \FooB   \FooB 12.3pt
\protected\def\FooC   {\the\dimexpr\FooA +\FooB\relax}

So you can now figure how 'cx' is defined in a dynamic way.


Hans

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                                           Hans Hagen | PRAGMA ADE
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