Thank you a lot for the explanation! It makes more sense now and
definitively is something very promising to play with. Wrt the module
itself, is it possible to consider language-dependent labels? I noticed
"\sin" is "sin" when it should be "sen" once the module is loaded.

Jairo

El dom, 23 de may. de 2021 a la(s) 09:35, Hans Hagen (j.hagen@xs4all.nl)
escribió:

> On 5/23/2021 3:45 PM, Jairo A. del Rio wrote:
> > El dom, 23 de may. de 2021 a la(s) 04:51, Hans Hagen (j.hagen@xs4all.nl
> > <mailto:j.hagen@xs4all.nl>) escribió:
> >
> >     On 5/22/2021 11:34 PM, Jairo A. del Rio wrote:
> >      > Hi. Is \thewithproperty documented elsewhere? Is this a new
> >     primitive?
> >      > It looks interesting.
> >     In the case of the \sin trick particular case \let\computer\the would
> >     also work; i added the \thewithproperty<number> feature just because
> i
> >     expect that users can come up with variants (like \drawme\sin ...)
> >     which
> >     then would adapt behaviour (via \dowithproperty2).
> >
> >
> > Having flags for computing and drawing would be awesome. I think it
> > would nicely extend ConTeXt's drawing features...
> >
> >     So, indeed it's a new primitive but (for now) only used with these
> lua
> >     hacks. Actually it's no big deal to reimplement \thewithoutunit<dim>
> as
> >
> >
> > So, is this Lua-specific?
>
> it relates to teh way tex sees things ... thihnk of
>
>    \dimen0=10pt
>
> where \dimen expects a number, optional equal and value
>
> while
>
>    \the\dimen0
>
> the '\the' expects all kind of things, with '\dimen' being one of then
> in which case its value is serialized
>
> in order to implement 'new primitives' using lua (like some that need to
> be implemented for compatibility reasons due to the backend differences)
> we need to be able to distinguish between setting and getting a value
>
> so in that sense it's indeed lua specific: a specific class of lua
> functions knows if it's triggered by serialization
>
> and that is what we 'kind of' abuse here and also why i did add this
> additional 'pseudo prefix' so that we ca ndo more clever things if we
> want to
>
> >         \thewithoutunit{\dowithproperty1\the}
> >
> >     and then
> >
> >         \thewithcmunit{\dowithproperty2\the}
> >
> >     to serialize the dimension in cm but normally i need to "wonder for a
> >     while if it makes sense".
> >
> >     Btw, adding primitives (related to the token related bits and pieces
> of
> >     the engine) only makes sense if the gain is in
> >
> >     -- avoiding clumsy code: although that can hurt someones pride and
> joy
> >     over a nice and complex macro doing the same ... don't worry, i threw
> >     away plenty of code by now
> >
> >     -- significant performance gain: which is seldom the case (there
> really
> >     is not much to gain, at least not in context which is rather
> optimized
> >     already)
> >
> >     -- giving way less noise in tracing: which for me is a good reason
> >     (tracing changed a bit anyway)
> >
> >     -- not adding much code to the engine or the need to refactor:
> although
> >     for some luametatex extensions some internals had to change
> >     fundamentally
> >
> >     a good example is the extended macro argument handling: less clumsy
> tex
> >     code, a bit of performance gain and easier full expansion, way less
> >     tracing, but it violates the last argument because it did lead to
> some
> >     refactoring (i also had to make sure the extra overhead didn't slow
> >     down
> >     macro definitions and expansion)
>
> > I did the following and I have two questions:
> >
> > 1. What if I want to have more than one property? Say \plusone for
> > computation and \plustwo for drawing.
>
> you can do that but keep in mind that \compute is then an 'official'
> context one (bound to 1) and any other number can conflict with other
> context numbers in the future, so best start at 1000 or so for private
> ones
>
> > 2. What does 'usage="value"' mean in the implement function (looks new,
> > but I'm prolly wrong)?
>
> indeed, it is already there for a while and it lets the function
> definition follow a different route ... basically one that can follow
> \the; I suppose that I can also make 'property' a valid usage (alias)
>
> (btw often features like this are described in articles or wrapups inm
> documents in the distribution or even mentioned here but as usual with
> tex these things only make sense trigger usage when one really needs it)
>
> > \permanent\protected\def\drawme{\thewithproperty\plussix} %better than
> 666
>
> or 31415 to fit in the tex numbering
>
> > \startluacode
> > local interfaces = interfaces
> > local implement = interfaces.implement
> > local context = context
> > local drawme_code = 6
> > local drawing = [==[
> > draw fullcircle scaled 10mm;
> > draw fullcircle shifted up scaled 5mm;
> > draw fulltriangle shifted (up+1/2right) scaled 5mm;
> > ]==]
> >
> >
> > local function chicken(value)
> > if value == "value" or value == drawme_code then
>
> no need to check for "value" unless you also want:
>
> \the\chicken
>
> > context.metafun.start()
> > context.metafun(drawing);
> > context.metafun.stop()
> > --elseif then ...
> > else
> > context("Chicken!")
> > end
> > end
> >
> > implement{
> > name = "chicken",
> > public = true,
> > usage = "value", --What does it do?
> > overload = true,
> > actions = chicken
> > }
> >
> > \stopluacode
> >
> > \starttext\chicken\ and \drawme\chicken\stoptext
> indeed an example of usage, and as with the mathfun, it saves a ton of
> macros like \drawchicken and so
>
> so now you next challenge is to pass arguments so here a next phase
>
> \permanent\protected\def\drawme{\thewithproperty1006 }
>
> \startluacode
>
> local interfaces = interfaces
> local implement = interfaces.implement
> local context = context
>
> local d = {
>      chickcolor = "red",
>      beakcolor  = "green",
> }
>
> local drawing = utilities.templates.replacer [==[
>      draw fullcircle scaled 10mm withcolor %chickcolor%;
>      draw fullcircle shifted up scaled 5mm;
>      draw fulltriangle shifted (up+1/2right) scaled 5mm withcolor
> %beakcolor%;
> ]==]
>
>
> local function chicken(value)
>         if value == 1006 then
>          local t = tokens.scanners.hash() or { }
>          table.setmetatableindex(t,d)
>          context.metafun.start()
>              context.metafun(drawing(t,v))
>                 context.metafun.stop()
>         else
>                 context("Chicken!")
>         end
> end
>
> implement{
>         name     = "chicken",
>         public   = true,
>         usage    = "value", --What does it do?
>         overload = true,
>         actions  = chicken
> }
>
> \stopluacode
>
> \starttext
>      \chicken\ and \drawme\chicken
>      \chicken\ and \drawme\chicken[chickcolor=blue,beakcolor=cyan]
> \stoptext
>
> (just to remind readers of the real old and probably seldom used
> template mechanism)
>
> Hans
>
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>                                            Hans Hagen | PRAGMA ADE
>                Ridderstraat 27 | 8061 GH Hasselt | The Netherlands
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