How to get text representation of composite value?

Hello,
I'd like to ask you for a help. I'm in trouble with $subj. I need something like documentation of PostgreSQL in chapter 8.11.5 says.
Inside trigger I have record type NEW which is composite type. How could one do something like :

text_var:=to_char(NEW)

So if NEW.at1='test' and NEW.at2=100 I would get string: 'test',100

But the problem is then if trigger is generally used for many tables, I
don't know number of elements and so on.

As I know, for element types are defined output function, and I can use this:
SELECT textin(point_out('(1,1)'::point))::varchar;

Anybody can help me?
P.S. pl/pgsql would be best way if it possible.

David F