[NTG-context] Using lua to define a macro with one optional parameter in brackets

[Taco Hoekwater]

> On 08 Jul 2015, at 11:05, Jaroslav Hajtmar <hajtmar at gyza.cz> wrote:
> 
> Hello ConTeXist.
> 
> Within the one very complex problem I need to solve the following case. I want using lua code to define a macro with one optional parameter in brackets.

Simplest solution I know is this:

\startluacode
interfaces.definecommand ('dolastname', {
    arguments = { { "option", "string" }  },
    macro = function (opt_1)
       if #opt_1>0 then context(opt_1) else context('nothing') end 
    end
})
interfaces.definecommand ('lastname', {
    macro = function ()
       context.dosingleempty()
       context.dolastname()
    end
})
\stopluacode

Best wishes,
Taco