I disagree. A type constraint for a struct would definitely provide compile-time guarantee that only a struct can be used.
On Thursday, June 25, 2020 at 8:18:13 AM UTC+10, Ian Lance Taylor wrote: > > On Wed, Jun 24, 2020 at 12:22 PM David Finkel <david...@gmail.com > <javascript:>> wrote: > > > > On Wed, Jun 24, 2020 at 9:34 AM Robert Engels <ren...@ix.netcom.com > <javascript:>> wrote: > >> > >> Generics will not solve this fully anyway - you’ll still need > reflection. Why not just return empty if the user doesn’t pass a struct? > >> > > That sounds like a bug waiting to happen. > > > > I have a library with a similar reflection-related use-case involving > reflection, which currently panics when it gets a non-struct-type. It would > be nice to have compile-time type-checking, if possible. > > > Generics don't solve all problems. I'm inclined to say that this is a > problem that they don't solve. Sorry. > > Ian > > > > > >> On Jun 24, 2020, at 8:29 AM, Pee Jai <p...@pjebs.com.au <javascript:>> > wrote: > >> > >> > >> Here is my use case: > https://godoc.org/github.com/rocketlaunchr/react#UnmarshalState > >> > >> That function has an argument that accepts only a struct. I use the > reflect package to iterate over the structs fields (and also to check if it > actually is a struct). The function has notapplicability for non-structs. > >> > >> Currently I have to notify the user via documentation that only a > struct is allowed since the type is officially an `interface{}`. This is > very crude. > >> > >> If there was a way to add a type constraint for only structs, then I > don't need to use documentation, notwithstanding the use of reflect package > to iterate over the struct fields. > >> > >> On Wednesday, June 24, 2020 at 10:34:40 AM UTC+10, Ian Lance Taylor > wrote: > >>> > >>> On Mon, Jun 22, 2020 at 7:08 PM Pee Jai <p...@pjebs.com.au> wrote: > >>> > > >>> > I can't find a way to constrain for just structs. I don't want > primitives. > >>> > >>> The design draft doesn't provide any mechanism for a type constraint > >>> to match any arbitrary struct type, and not any other kind of type. > >>> > >>> But it's not clear why that would be useful. The only things you can > >>> do with a value of an arbitrary struct type are things that you can do > >>> with a value of any arbitrary type. > >>> > >>> Ian > >> > >> -- > >> You received this message because you are subscribed to the Google > Groups "golang-nuts" group. > >> To unsubscribe from this group and stop receiving emails from it, send > an email to golan...@googlegroups.com <javascript:>. > >> To view this discussion on the web visit > https://groups.google.com/d/msgid/golang-nuts/e86e677b-784d-47c5-b8b9-aedc37977ba5o%40googlegroups.com. > > > >> > >> -- > >> You received this message because you are subscribed to the Google > Groups "golang-nuts" group. > >> To unsubscribe from this group and stop receiving emails from it, send > an email to golan...@googlegroups.com <javascript:>. > >> To view this discussion on the web visit > https://groups.google.com/d/msgid/golang-nuts/8013EEB8-78E6-455D-B846-8A826682B879%40ix.netcom.com. > > > > > > -- > > You received this message because you are subscribed to the Google > Groups "golang-nuts" group. > > To unsubscribe from this group and stop receiving emails from it, send > an email to golan...@googlegroups.com <javascript:>. > > To view this discussion on the web visit > https://groups.google.com/d/msgid/golang-nuts/CANrC0BgyoPvEWJEOOrJwt-3qfLvSxc6CX9yLoYBPxYZV8GBZLg%40mail.gmail.com. > > > -- You received this message because you are subscribed to the Google Groups "golang-nuts" group. To unsubscribe from this group and stop receiving emails from it, send an email to golang-nuts+unsubscr...@googlegroups.com. To view this discussion on the web visit https://groups.google.com/d/msgid/golang-nuts/b15a841e-46bd-450f-8c71-d4429700b050o%40googlegroups.com.
