[pstricks] Naive question

[Pedro Jorge Caridade]

I'm starting to get inside pstricks codes, and try to write some very
simple. I have two questions, very naive, that I don't understand very
clearly:

How to pass arguments to my functions. For example I have this simple
code:
\makeatletter
\def\ArrowPolygon{\pst at object{ArrowPolygon}}
\def\ArrowPolygon at i%
{\@ifnextchar[{\ArrowPolygon@@ii}{\ArrowPolygon@@ii[]}}
\def\ArrowPolygon@@ii[#1](#2)(#3,#4)(#5,#6){%
\typeout#2%
\typeout#3%
\typeout#4%
\typeout#5%
\typeout#6%
}
....
\ArrowPolygon(1,-1)(20,5)(10,15)
....
The output confused me: 1,2,4,1,1. It saves only the first character.

-What should I do to pass the complete value? 

-In the case of argument #2, I would like to pass everything. Is there
then a way to then decompose in two values, or its better to use two
arguments instead of one?
 
Sorry for this very naive questions. 
Pedro