Re: Best way to create a sequence generator at run time?

I'm converging on a good solution, but have just one (hopefully) problem left.
I need to get the nextval for a sequence whose name has been stored, and is thus
not available prior to runtime.  I am trying to use EXECUTE, but can't seem to get
it right.  Suggestions?

Here's the function extract in question:

create or replace function ...
) returns bigint as
$$
declare
    self subsystem%rowtype; -- has an attribute where the sequence name is stored
begin
    select * from subsystem into strict self where (name = p_subsystem and domain = p_domain);

    -- self.cnum_generator is a text value holding the name of the previously created sequence
    -- I've tested to ensure that it is holding the correct value, so no worries there, it is a valid sequence

    -- Now here is the trouble - none of these statements seem to work or parse correctly:

    return execute 'nextval(' || self.cnum_generator || ')';  -- NOPE

    new_num := nextval(self.cnum_generator);  -- I didn't expect this one to work, but might as well try, NOPE

    return query execute 'nextval( $1 )' using self.cnum_generator;  -- no good either

    return query execute 'nextval(' || self.cnum_generator || ')';  -- NOPE

    -- accck!  Phhht!  Help!