On Tue, Mar 1, 2011 at 5:17 PM, Pavel Stehule <pavel.stehule@gmail.com> wrote:
> Hello
>
> 2011/3/2 Pierre Racine <Pierre.Racine@sbf.ulaval.ca>:
>> Hi,
>>
>> I would like to write a generic plpgsql function with a text parameter being a callback function name so that my
generalfunction 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.
merlin