Sam Mason <sam@xxxxxxxxxxxxx> writes: > On Sat, Oct 03, 2009 at 12:48:57PM -0400, Tom Lane wrote: >> I think the reason CREATE CAST exists is exactly that the cast mechanism >> *isn't* intended to provide conversions between any arbitrary pair of >> datatypes. It's only intended to provide conversions in those cases >> where the conversion semantics are obvious to some degree or other. > Yup, but the decision to officially bless some code as being a cast > rather than "just" a function seems very arbitrary, I think this is why > I don't understand its purpose. It's useful when the conversion semantics are sufficiently natural that you want the conversion to be applied implicitly. I agree that the explicit CAST syntax hasn't got very much to recommend it over a function call. That part you can blame on the SQL committee ;-) ... the historical PostQUEL syntax for this was exactly a function call, and you can still write it that way if you choose. regards, tom lane -- Sent via pgsql-general mailing list (pgsql-general@xxxxxxxxxxxxxx) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-general
