automatic build of return type

Hi all

I am coverting a database with several stored procedures from MS SQL Server
to PostgreSQL 8.2 and I have the following doubt:
With MS Sql a stored procedure containing the statement "SELECT * FROM
TABLE_A INNER JOIN TABLE_B" automatically creates and return a recordset
with all the fields of TABLE_A followed by all the fields of TABLE,
instead, in my opinion, in a Postgresql function (language plpgsql) I MUST
create by hand a type containing all the fields (or create BY hand a list in
the declare space); The question is: It exist a method to create
automatically the return type to avoid to write it by hand?

Thank you.

Domenico