Re: [NTG-context] About the use of command handlers

29 May 2020


      On 5/29/2020 6:29 AM, Jairo A. del Rio wrote:
...
Hello list! I was reading the following:
https://wiki.contextgarden.net/Style_Alternatives
I wanted to figure out how to make a simple module. However, there's a 
point in the example below which I don't understand
% macros=mkvi
\startmodule[look]
\unprotect
\writestatus{loading}{ConTeXt User Module / look} 
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
\installnamespace {look}
\installcommandhandler \????look {look} \????look
\appendtoks
\setuevalue{\currentlook}{\do_look{\currentlook}}
\to \everydefinelook
\unexpanded\def\do_look#id{%
\edef\currentlook{#id}%
\dosingleempty\do_do_look%
}
\def\do_do_look[#parms]#content{%
\begingroup
\iffirstargument\setupcurrentlook[#parms]\fi
%This handles style and color
\uselookstyleandcolor\c!style\c!color%
#content%
\endgroup%
}
\protect %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
\stopmodule
What have I to do if, instead of "color" or "style", I want to use 
another keyword, as "dummy" and get its value? Something like
\definelook[lol][dummy = blabla]
\lol{words}
%e.g. words \emph{blabla} or something similar
so "lol" is a word, a number or whatever. I've read something about 
command handlers, but I'm having a hard time trying to understand them. 
Thank you in advance!
% macros=mkvi
\unprotect

\installnamespace {look}

\installcommandhandler \????look {look} \????look

\appendtoks
     \setuevalue{\currentlook}{\module_look_do{\currentlook}}
\to \everydefinelook

\unexpanded\def\module_look_do#id%
   {\edef\currentlook{#id}%
    \dosingleempty\module_look_do_do}

\def\module_look_do_do[#parms]#content%
   {\dontleavehmode
    \begingroup
    \iffirstargument
      \setupcurrentlook[#parms]%
    \fi
    \doifsomething{\lookparameter{title}}
      {\begingroup
         \uselookstyleandcolor\c!headstyle\c!headcolor
         \lookparameter{title}%
         \lookparameter{separator}%
       \endgroup}%
    \uselookstyleandcolor\c!style\c!color
    #content%
    \endgroup}

\protect

\starttext

\setuplook[separator={: }]

\definelook[lol][color=red,headcolor=green]

\lol[title=blabla]{words}

\stoptext


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