Issue with \handletokens\with and Lua-defined macros

Issue with \handletokens\with and Lua-defined macros

[Jairo A. del Rio]

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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?

Thanks in advance. Cordially,

Jairo

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Re: Issue with \handletokens\with and Lua-defined macros

[Hans Hagen]

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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                                           Hans Hagen | PRAGMA ADE
               Ridderstraat 27 | 8061 GH Hasselt | The Netherlands
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___________________________________________________________________________________
If your question is of interest to others as well, please add an entry to the Wiki!

maillist : ntg-context@ntg.nl / http://www.ntg.nl/mailman/listinfo/ntg-context
webpage  : http://www.pragma-ade.nl / http://context.aanhet.net
archive  : https://bitbucket.org/phg/context-mirror/commits/
wiki     : http://contextgarden.net
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