trigger sub-functions

is there any way to get access to the new and old records created by a
trigger in the function it calls?

i.e., if i have

create trigger after_insert after insert on foo
execute procedure trigger_after_insert_foo();

is there any way to do something like the following...

create function trigger_after_insert_foo() returns opaque as '
begin
    /*
     * have some function like sub_foo() that accesses new and          * returns it
somehow.
     */
    return new;
end
' language 'plpgsql';

-tfo