On Mon, 5 Feb 2007, Aditya Mahajan wrote:
> Hi,
>
> I wand to write a macro, that handles both [] and {} as optional
> arguments. For example, I have a command with three optionl arguments
>
> [#1][#2]#3
>
> I want
>
> \command to give #1=\empty, #2 = \empty, #3 = \empty
>
> \command [1] to give #1=1, #2 empty, #3 empty,
>
> \command [1] {3} to give #1=1, #2 empty, #3 = 3
>
> \command [1] [2] {3} to give #1=1, #2=2, #3=3
>
> \command {3} to give #1=empty, #2=empty, #3=3.
>
> I tried the following macro, it works except for \command[1][2]{3}.
>
> \def\finalcommand[#1][#2]#3%
> {1 :-> (#1), 2 :-> (#2), 3 :-> (#3)}
>
> \def\command%
> {\dodoubleempty\docommand}
>
> \def\docommand[#1][#2]%
> {\dodoublegroupempty{\finalcommand[#1][#2]}}
>
> \starttext
>
> \command
>
> \command [1]
>
> \command [1] {3}
>
> \command [1] [2] {3}
>
> \command {3}
>
> \stoptext
>
> which gives
>
> 1 :-> (), 2 :-> (), 3 :-> ()
> 1 :-> (1), 2 :-> (), 3 :-> ()
> 1 :-> (1), 2 :-> (), 3 :-> (3)
> 1 :-> (1), 2 :-> (2), 3 :-> () 3 <--------- This does not work
> 1 :-> (), 2 :-> (), 3 :-> (3)
>
> Can someone suggest a better way to do this?
I found another way, I hope that it has no gotcha's
\def\finalcommand[#1][#2]#3%
{1 :-> (#1), 2 :-> (#2), 3 :-> (#3)}
\def\command%
{\dodoubleempty\docommand}
\def\docommand[#1][#2]%
{\def\useoneargument##1{\finalcommand[#1][#2]{##1}}
\def\fakeoneargument{\finalcommand[#1][#2]{}}
\doifnextcharelse\bgroup{\useoneargument}{\fakeoneargument}}
Aditya
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