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. > Since that's somewhat in the eye of the beholder, we allow the user > to adjust edge cases by creating/removing casts --- but there's no > expectation that when you define a new datatype, you'll provide casts > to or from unrelated types. I know there's no expectation to create any casts. I think what I'm confused about is why anyone would ever bother creating any in the first place. I have a feeling I may have used the functionality once, but I can't think why or for what now. Having a function seems just as expressive to me, which is why I think I'm missing the point. -- Sam http://samason.me.uk/ -- Sent via pgsql-general mailing list (pgsql-general@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-general
