On 2017-01-26 20:29:06 -0500, Tom Lane wrote: > Andres Freund <and...@anarazel.de> writes: > > On 2016-12-31 12:08:22 -0500, Peter Eisentraut wrote: > >> This is inspired by the dynamic_cast operator in C++, but follows the > >> syntax of the well-known makeNode() macro. > > > The analogy to dynamic_cast goes only so far, because we don't actually > > support inheritance. I.e. in c++ we could successfully cast SeqScanState > > to a > > PlanState, ScanState and SeqScanState - but with our model only > > SeqScanState can be checked. > > Yeah, I was thinking about that earlier --- this can only be used to cast > to a concrete node type, not one of the "abstract" types like Plan * or > Expr *. Not sure if that's worth worrying about though; I don't think > I've ever seen actual bugs in PG code from casting the wrong thing in that > direction. For the most part, passing the wrong thing would end up firing > a default: case in a switch, or some such, so we already do have some > defenses for that direction.
Yea, I'm not actually worried about it - I was more generally remarking on the analogy made by Peter. For a second I was considering bringing up the analogy in a comment or such, and this was one of a number of arguments that made me disregard that idea. Andres -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
