"Merlin Moncure" <[EMAIL PROTECTED]> writes: >> typedef void *(*PGobjectEventProc)(PGobjectEventId evtId, ...); >> int PQregisterObjectEventProc(PGconn*, PGobjectEventProc); >> void *PQeventData(PGconn *, PGobjectEventProc); >> void *PQresultEventData(PGresult *, PGobjectEventProc);
> This provides what we need...a key to lookup the hook data without > using a string. Also, it reduces the number of exports (it's a little > easier for us, while not essential, to not have to register each > callback individually). Also, this AFAICT does not have any ABI > issues (no struct), and adds less exports which is nice. We don't > have to 'look up' the data inside the callbacks..it's properly passed > through as an argument. While vararg callbacks may be considered > unsafe in some scenarios, I think it's a good fit here. I don't think varargs callbacks are a good idea at all. Please adjust this to something that doesn't do that. Also, haven't you forgotten the passthrough void *? If you really want only one callback function, perhaps what would work is typedef void (*PGeventProc) (PGeventId eventId, const void *eventInfo, void *passthrough); int PQregisterEventProc(PGconn *conn, PGeventProc proc, void *passthrough); where eventInfo will point to one of several exported struct types depending on the value of eventId. With this approach, you can add more fields to the end of any one such struct type without creating ABI issues. I have little confidence in being able to make similar changes in a varargs environment. Also, even if varargs are safe they'd be notationally unpleasant in the extreme. varargs are just a PITA to work with --- you'd have to do all the decoding in the first-level hook routine, even for items you weren't going to use. With something like the above all you need is a switch() and some pointer casts. regards, tom lane -- Sent via pgsql-patches mailing list (pgsql-patches@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-patches