On Tue, 13 Oct 2020, Pablo Rodriguez wrote:

> Dear list,
> 
> I have the following sample:
> 
>   \starttext
>   \def\numbersfname
>     {\cldcontext{string.match([[\env{fname}]], "\letterpercent d+")}}
>   \ctxlua{ c = context.getvariable("environment", "fname") or "a" }
>   \ctxlua{ d = [[\env{fname}]] }
> 
>   tex: \numbersfname\\
>   \doifelse{}
>       {123}{yes}{no}\\
>   c: \cldcontext{c}\\
>   \doifelse{\cldcontext{c:match("\letterpercent d+")}}
>       {123}{yes}{no}\\
>   d: \cldcontext{d}\\
>   \doifelse{\cldcontext{d:match("\letterpercent d+")}}
>       {123}{yes}{no}
>   \stoptext
> 
> For compilation, I run the command:
> 
>   context --purgeall --arguments=fname={abc123} test-file.tex
> 
> These things are failing:
> 
> 1. I don’t know how to get \numbersfname equal to "123". I don’t know
> what I’m doing wrong.
> 
> 2. Is there no Lua version of \getvariable{...}{...}?
> 
> 3. I’m trying this on a Linux box, but on Windows I would say that Lua
> variable "d" is empty.
> 
> I need to get the number from \env{fname} and I don’t know what I’m
> missing. \doif is the way to test whether it’s right.
> 
> Could anyone explain me what I’m missing here?

I find it simpler to write macros where there is  clean communicating between tex and lua. For example:

    \startluacode
      userdata = userdata or {}
      function userdata.numbersfname(name)
          return string.match(name, "%d+")
      end
    \stopluacode

    \define[1]\numbersfname
        {\cldcontext{userdata.numbersfname([==[#1]==])}}

    \starttext
    \numbersfname{abc123}

    \numbersfname{\env{fname}}
    \stoptext


Aditya