Dynamic fieldname with NEW structure in trigger function?

Hi List!

I have discussed the following problem with pl/pgsql on irc://freenode/postgresql. <irc://freenode/postgresql>

Christopher Kings-Lynne has asked me to post the problem here as a feature request, so here goes:
I think it is best formulated in plpgsql code below.

Kris Jurka has mentioned that something like this might work with pl/tcl and pl/python.
I am not experienced with those however, so I can't comment on that

CREATE FUNCTION trg_log_up_other() RETURNS trigger
AS '
DECLARE
sql_txt text;
up_table text;
up_field text;
BEGIN
up_table := TG_ARGV[0];
up_field := TG_ARGV[1];

sql_txt := ''UPDATE ''
|| quote_ident(up_table)
|| '' SET somefield = somevalue''
|| '' WHERE ''
|| quote_ident(up_field)
|| '' = ''
|| NEW.staticname_id;
-- ^^^^^^^^^^^^^^^^^^^^^ !!! last line = EVIL HACK !!!
-- I want a dynamic name passed by TG_ARGV[2] instead of staticname_id.
-- But NEW is not known inside EXECUTE, so it throws an error and does not evaluate.
-- But how can i evaluate a dynamic field if not with EXECUTE?
-- How do i get to the value of the field?

EXECUTE sql_txt;

return NEW;

END;
' LANGUAGE plpgsql;

Thanx for considering.
Please cc me on replies.

Regards
Erwin Brandstetter