Re: [NTG-context] \do(single|double|etc)empty behaviour

15 Dec 2010


      Wolfgang Schuster  writes:
...
Am 15.12.2010 um 19:40 schrieb Marco Pessotto:
...
Hello there.
I was writing a small macro to emulate a custom \part command, and I
broke my head against \dosingleempty (but finally I won).
[…]
It's unclear to me how the arguments are passed between macros.
Probably it's just a matter of knowledge of TeX macro programming
(which obviously I don't have).
Your test with \iffirstargument fails because you perform it after
\startalignment which has itself a argument which sets
\iffirstargument to true, a better way to check for content of the
optional argument is \doifsomethingelse.
\def\talpart
  {\dosingleempty\dotalpart}
\def\dotalpart[#1]#2%
  {\page[right]
   \blank[force,2*big]
   \startalignment[center]
   \doifsomethingelse{#1}
     {{\bfc#1}\writetolist[talpart]{}{#1. #2}}
     {\writetolist[talpart]{}{#2}}%
   \blank[2*big]
   {\bfd#2}
   \stopalignment
   \page[left]}
Wolfgang
Thanks a lot for your explanation. I've added a "pitfalls" section to
http://wiki.contextgarden.net/Commands_with_optional_arguments#Pitfalls
(well, it was a pitfall at least for me)

-- 
Marco