ai2472206007@yeah.net schrieb am 22.10.2024 um 07:32:
Thank you so much. I think I understand its usage.
Also, regarding the "ifargument" command you mentioned, is it counting from 0 and then checking the arguments one by one? Because I only learned "iffirstargument", "ifsecondargument" from the wiki. Perhaps we should update the section on the wiki on defining optional parameters.
You can check individual argument with the old and new method but there are differences because the new \ifparameter conditional gives a false result when you set the optional argument but leave it empty. %%%% begin example \def\oldargumentcheck {\dotripleempty\dooldargumentcheck} \def\dooldargumentcheck[#1][#2][#3]% {\iffirstargument First optional argument is used.\par \else First optional argument isn't used.\par \fi \ifsecondargument Second optional argument is used.\par \else Second optional argument isn't used.\par \fi \ifthirdargument Third optional argument is used.\par \else Third optional argument isn't used.\par \fi} \tolerant\def\newargumentcheck[#1][#2][#3]% {\ifparameter#1\or First optional argument is used.\par \else First optional argument isn't used or empty.\par \fi \ifparameter#2\or Second optional argument is used.\par \else Second optional argument isn't used or empty.\par \fi \ifparameter#3\or Third optional argument is used.\par \else Third optional argument isn't used or empty.\par \fi} \starttext \oldargumentcheck[][foo] \blank \newargumentcheck[][bar] \stoptext %%%% end example When you care only about the number of argument you would use nested argument checks in the old system but the new \ifarguments conditional uses branches for each case like \ifcase. The order for the number of arguments is also reversed, the old system starts with the case for all argument and ends with zero arguments while the new check start with zero arguments and ends with all of them. %%%% begin example \def\oldcommand {\dotripleempty\dooldcommand} \def\dooldcommand[#1][#2][#3]% {\ifthirdargument Three optional arguments are used.\par \else\ifsecondargument Two optional arguments are used.\par \else\iffirstargument One optional argument is used.\par \else No optional argument is used.\par \fi\fi\fi} \tolerant\def\newcommand[#1][#2][#3]% {\ifarguments No optional argument is used.\par \or One optional argument is used.\par \or Two optional arguments are used.\par \or Three optional arguments are used.\par \fi} \starttext \oldcommand[][] \blank \newcommand[][] \stoptext %%%% end example Wolfgang