Am 06.11.2013 um 20:26 schrieb Pablo Rodriguez :

Dear list,

I’m trying to define a command that has a conditional argument:

\def\MyCommand#1#2#3{#1, #2, \doifemptyelse{#3}{#1}{#3}} \starttext \MyCommand{first}{second} \stoptext

The problem is that \doifemtpyelse only works if there the third argument is there as {}. And the third argument is actually an exception to workaround an unwanted behavior of the command in very few exceptional cases.

Is there no way to make \MyCommand above work with \doifemptyelse even if its third argument is not defined?

\def\MyCommand {\dotriplegroupempty\doMyCommand} \def\doMyCommand#1#2#3% {#1, #2, \ifthirdargument #3\else #1\fi} \starttext \MyCommand{first}{second}{third} \MyCommand{first}{second} \stoptext Wolfgang