[NTG-context] \doifelse not working, \doiftextelse breaking

[Wolfgang Schuster]

Pablo Rodriguez schrieb am 09.10.2020 um 15:58:
> Dear list,
> 
> I have the following sample:
> 
>      \starttext
>      \startluacode
>      function document.starts_with(str, start)
>        if str:sub(1, #start) == start then
>          context(start)
>        end
>      end
>      \stopluacode
> 
>      \unexpanded\def\startswith[#1][#2]
>          {\cldcontext{document.starts_with("#1", "#2")}}


You need a % at the end of the definition, otherwise TeX expects a space 
after the second argument to end the command.

\unexpanded\def\startswith[#1][#2]%
   {...}


To improve your command and allow a space between both arguments you can use

\unexpanded\def\startswith
   {\dodoubleargument\dostartswith}

\def\dostartswith[#1][#2]%
   {...}

or just add a dummy parameter and use #1 and #3 to pass the arguments

\unexpanded\def\startswith[#1]#2[#3]%
   {...}


Wolfgang