trigger inheritance

In Postgres, is it possible to write a (trigger) function for a table "parent" that is inherited automatically by tables "children" ?

If so, how?

And how would this trigger function access _all_ columns in the table "children"?

Example:

create table parent (
id serial,
crc32 int4
);

create function calculate_crc()
returns opaque
as 'BEGIN
new.crc32 = my_external_crc_func();
-- my_external_crc_func must be able to "see" all columns of "new"
END;'
language 'plpgsql';

CREATE TRIGGER inherited
BEFORE INSERT OR UPDATE
ON parent
FOR EACH ROW
EXECUTE PROCEDURE calculate_crc();

create table child (
something text
) inherits (parent);

When I try this, "child" does not seem to inherit the trigger. What's more - I don't know how to let "my_external_crc_func" (loaded dynamically) can "see" all columns in "child".

Who can help me?

Most thankful for any hints,
Horst