Re: How to get parameters in lua

[Hans Hagen <pragma@wxs.nl>]

On 9/19/2014 9:30 AM, Christoph Reller wrote:
> Hi,
>
> \installcommandhandler nicely provides (among others) \define<name> and
> \setup<name> commands. Thus it is easy to provide a key with
> \setup...[key=value] and to read the value of such a key with
> \<name>parameter{key}.
>
> My question is: How do I read the value of a key defined with
> \setup...[key=value] on the lua side? If I use
>    context.<name>parameter("key")
> then the value of key is printed directly. I want to be able to read
> that value and use it in lua with something like
>    myvariable = context.?whatfunction?("key")
>
> Here is some example code:
>
> \unprotect
>
> \startluacode
>    function myfun(parameters,content)
>      context("From lua: Parameters: ")
>      context(parameters)
>      context.elemparameter("gkey") -- directly prints the parameter
>      context.par()
>    end
> \stopluacode
>
> \installnamespace{elem}
> \installcommandhandler \????elem {elem} \????elem
> \appendtoks
>    \setuevalue{\currentelem}{\elem_cmd{\currentelem}}%
> \to \everydefineelem
>
> \unexpanded\def\elem_cmd#environment{%
>    \edef\currentelem{#environment}%
>    \dosingleempty\elem_cmd_parameters}
>
> \def\elem_cmd_parameters[#parameters]#content{%
>    \setupcurrentelem[#parameters]
>    From \TeX\: Parameters: key=\elemparameter{key},
> gkey=\elemparameter{gkey}\par
>
> \ctxlua{myfun(\!!bs#parameters\!!es,\!!bs\normalunexpanded{#content}\!!es)}
> }
>
> \defineelem[base]
> \setupelem[gkey=gval]
>
> \protect
>
> \starttext
>
> \base[key=val]{Hello}
>
> \stoptext
>
> Thank you for any feedback,

something like this ... keep in mind that there is no grouping in lua

% macros=mkvi

\unprotect

\installnamespace{elem}

\installcommandhandler \????elem {elem} \????elem

\startluacode
     userdata.elem = { data = { [""] = { } } }

     function userdata.elem.define(namespace,parent)
         print("define",namespace,parent)
         userdata.elem.data[namespace] = { }
         if namespace ~= parent then
 
table.setmetatableindex(userdata.elem.data[namespace],userdata.elem.data[parent])
         end
     end

     function userdata.elem.setup(namespace,key,gkey)
         print("setup",namespace,key,gkey)
         userdata.elem.data[namespace].key = key
         userdata.elem.data[namespace].gkey = gkey
     end

     function userdata.myfun(namespace,one,two)
         context.par()
         context("elem: one=%s",userdata.elem.data[namespace][one])
         context.par()
         context("elem: two=%s",userdata.elem.data[namespace][two])
         context.par()
     end
\stopluacode

\appendtoks
     \setuevalue{\currentelem}{\elem_cmd{\currentelem}}%
     \ctxlua{userdata.elem.define("\currentelem","\currentelemparent")}%
\to \everydefineelem

\appendtoks
 
\ctxlua{userdata.elem.setup("\currentelem","\elemparameter{key}","\elemparameter{gkey}")}%
\to \everysetupelem

\unexpanded\def\elem_cmd#environment%
   {\edef\currentelem{#environment}%
    \dosingleempty\elem_cmd_parameters}

\def\elem_cmd_parameters[#parameters]#content%
   {\setupelem[\currentelem][#parameters]
    From \TeX\: Parameters: key=\elemparameter{key}, 
gkey=\elemparameter{gkey}\par
    \ctxlua{userdata.myfun("\currentelem","key","gkey")}}

\defineelem[base]
\setupelem[gkey=gval]

\protect

\starttext

\base[key=val]{Hello}

\stoptext

A simpler alternative is:

% macros=mkvi

\unprotect

\installnamespace{elem}

\installcommandhandler \????elem {elem} \????elem

\startluacode
     userdata.elem = { data = {  } }

     function userdata.elem.sync(key,gkey)
         userdata.elem.data.key = key
         userdata.elem.data.gkey = gkey
     end

     function userdata.myfun(one,two)
         context.par()
         context("elem: one=%s",userdata.elem.data[one])
         context.par()
         context("elem: two=%s",userdata.elem.data[two])
         context.par()
     end
\stopluacode

\appendtoks
     \setuevalue{\currentelem}{\elem_cmd{\currentelem}}%
\to \everydefineelem

\unexpanded\def\elem_cmd#environment%
   {\edef\currentelem{#environment}%
    \dosingleempty\elem_cmd_parameters}

\unexpanded\def\elem_sync
 
{\ctxlua{userdata.elem.sync("\elemparameter{key}","\elemparameter{gkey}")}}

\def\elem_cmd_parameters[#parameters]#content%
   {\setupcurrentelem[#parameters]
    \elem_sync
    From \TeX\: Parameters: key=\elemparameter{key}, 
gkey=\elemparameter{gkey}\par
    \ctxlua{userdata.myfun("key","gkey")}}

\defineelem[base]
\setupelem[gkey=gval]

\protect

\starttext

\base[key=val]{Hello}

\stoptext


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                                           Hans Hagen | PRAGMA ADE
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