[NTG-context] Issue with \handletokens\with and Lua-defined macros

Hans Hagen j.hagen at xs4all.nl
Mon Mar 29 19:16:27 CEST 2021


On 3/29/2021 10:54 AM, Jairo A. del Rio wrote:
> Hi list! See the following example:
> 
> \startluacode
> 
> userdata = userdata or {}
> 
> 
> --Toy example
> 
> --My actual function receives an argument, but the problem remains the same
> 
> 
> userdata.myfunction = function()
> 
> return
> 
> "343327959841638047651959775267761420323" ..
> 
> "657838053757849835434002826851807933276" ..
> 
> "324327913964298509889902373459201557839" ..
> 
> "84828001486412574060553756854137069878601"
> 
> end
> 
> 
> interfaces.implement{
> 
> name = "myfunction",
> 
> public = true,
> 
> actions =
> 
> function ()
> 
> context(userdata.myfunction())
> 
> end
> 
> }
> 
> \stopluacode
> 
> \def\colorfulnumbers#1{\colored[h=\luaexpr{40*#1},s=1,v=1]{#1}\ }%
> 
> \starttext
> 
> %It doesn't work
> 
> %\handletokens{\myfunction}\with\colorfulnumbers
> 
> \expandafter\handletokens\expandafter{\myfunction}\with\colorfulnumbers
> 
> \stoptext
> 
> 
> As readily seen from my example, I want to color each figure of the 
> numbers generated by a Lua function. However, the use of \expandafter's 
> is cumbersome in this case. I don't want to loop over the result in Lua 
> because I want to be able to apply \handletokens...\with... (or another 
> macro with a similar purpose) with different macros at the TeX end once 
> Lua has delivered results. How should I do it in ConTeXt?

In the usual way: different from what you might expect:

\startluacode
   userdata = userdata or { }

   userdata.myfunction = function()
     return
       "343327959841638047651959775267761420323" ..
       "657838053757849835434002826851807933276" ..
       "324327913964298509889902373459201557839" ..
       "84828001486412574060553756854137069878601"
end
\stopluacode

\doloopovermatch {.} {\luaexpr{userdata.myfunction()}} {%
     \colored[h=\luaexpr{40*#1},s=1,v=1]{#1}\space
}

or let youself surprise by:

\startluacode
     userdata = userdata or { }
     userdata.myfunction = function()
         return [[
             343327959841638047651959775267761420323
             657838053757849835434002826851807933276
             324327913964298509889902373459201557839
             84828001486412574060553756854137069878601
         ]]
     end
\stopluacode

\starttext

\doloopovermatch {\letterpercent d} {\luaexpr{userdata.myfunction()}} {%
     \colored[h=\luaexpr{40*#1},s=1,v=1]{#1}\space
}

(I think it's even documented somewhere.)

\handletokens is kind of mkii-ish and old fashioned.

Hans




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