On 2019-Dec-20, Paul A Jungwirth wrote: > Is it permitted to add casts with polymorphic inputs & outputs? Is > that something that we would actually want to do? I'd probably need > both the polymorphic and concrete casts so that you could still say > `int4range(1,2)::int4multirange`.
I'm embarrased to admit that I don't grok the type system well enough (yet) to answer this question. > Should I change the coerce code to look for casts among concrete types > when the function has polymorphic types? I'm pretty scared to do > something like that though, both because of the complexity and lest I > cause unintended effects. Yeah, I suggest to stay away from that. I think this multirange thing is groundbreaking enough that we don't need to cause additional potential breakage. > Should I just give up on implicit casts and require you to specify > one? That makes it a little more annoying to mix range & multirange > types, but personally I'm okay with that. This is my preferred > approach. +1 > I have some time over the holidays to work on the other changes Alvaro > has suggested. I hope not to have made things worse by posting a rebase. Anyway, that's the reason I posted my other changes separately. -- Álvaro Herrera https://www.2ndQuadrant.com/ PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services
