On Wed, Mar 2, 2011 at 8:34 AM, Dmitriy Igrishin <dmitigr@xxxxxxxxx> wrote: > 2011/3/2 Merlin Moncure <mmoncure@xxxxxxxxx> >> On Tue, Mar 1, 2011 at 5:17 PM, Pavel Stehule <pavel.stehule@xxxxxxxxx> >> wrote: >> > Hello >> > >> > 2011/3/2 Pierre Racine <Pierre.Racine@xxxxxxxxxxxxx>: >> >> Hi, >> >> >> >> I would like to write a generic plpgsql function with a text parameter >> >> being a callback function name so that my general function can call this >> >> callback function. e.g.: >> >> >> >> CREATE OR REPLACE FUNCTION ST_MyCallbackFunction(y int) >> >> RETURNS int AS $$ >> >> DECLARE >> >> BEGIN >> >> RETURN someCalculationBasedOnY; >> >> END; >> >> $$ LANGUAGE 'plpgsql'; >> >> >> >> CREATE OR REPLACE FUNCTION ST_MyGeneralFunction(callback text) >> >> RETURNS SETOF geomval AS $$ >> >> DECLARE >> >> x integer; >> >> y integer; >> >> BEGIN >> >> y := somecalculation; >> >> x := 'callback'(y); --This is what I need >> > >> > EXECUTE 'SELECT ' || callback || '($1)' USING y INTO x; >> > >> > there are no other way than EXECUTE >> > >> > attention - there is a sql injection risk >> >> another way if you are willing to write some C is to wrap and expose >> OidFunctionCall1 so it takes oid of function you want to call. > > As always, Merlin shows the uncommon thinking! :-) > Respect! Thank you, and I would like to be able to claim original invention of this idea, however I cannot: it came from none other than Tom Lane...http://postgresql.1045698.n5.nabble.com/improvise-callbacks-in-plpgsql-td2052928.html (for whom nary a day goes by that I am not thankful for his tireless efforts). merlin -- Sent via pgsql-general mailing list (pgsql-general@xxxxxxxxxxxxxx) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-general
