Definition of return types for own functions?

Hello all!

Is it possible to define a complex return type like a record in a function
without having some table around with the needed structure of the return
values?
For example: if i want a function that returns a date and an integer, i
create the function:

CREATE FUNCTION bla(text) RETURNS SETOF table_name AS '...

And i need the table table_name with the structure:
CREATE TABLE table_name( datum DATE, zahl INTEGER);

Can i somehow define this structe inside the function declaration without
having some empty tables or views around?

Thank you all!

Best regards,
Matthias