On Mon, Nov 4, 2024 at 2:40 AM hey...@gmail.com <hey....@gmail.com> wrote: > > Does that mean it's currently not possible to conditionally implement a > method based on type parameters?
I think that is https://go.dev/issue/65394. Ian > On Monday, November 4, 2024 at 1:47:30 PM UTC+8 Ian Lance Taylor wrote: >> >> On Sun, Nov 3, 2024 at 12:41 AM hey...@gmail.com <hey...@gmail.com> wrote: >> > >> > Not sure generic type alias is the solution, but what I'm trying to do is >> > I have a type like this >> > >> > type Map[K comparable, V any] struct { m map[K]V } >> > >> > and I want it to implement json.Unmarshaller to decode json objects, when >> > K's underlying type is string: >> > >> > type omap[K ~string, V any] = Map[K, V] >> > func (m *omap[K, V]) UnmarshalJSON(data []byte) error { >> > k := "a" >> > v :=1 >> > m[K(k)] = v >> > } >> > >> > Go 1.23 with the aliastypeparams flag enabled, currently complains "cannot >> > convert k (variable of type string) to type K". >> > >> > I wonder if using alias this way is wrong and if there exists another >> > solution? >> >> A type alias is just an alias. When you declare a method on the alias >> map, you are declaring a method on the type Map. That means that the >> ~string in the omap definition is ignored for the method definition; >> all that matters is the comparable constraint in the Map definition. >> You can't in general convert a string to a comparable 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 golang-nuts+unsubscr...@googlegroups.com. > To view this discussion visit > https://groups.google.com/d/msgid/golang-nuts/3b54013b-8d8d-4eb8-9e3b-77b50de0d3ebn%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 golang-nuts+unsubscr...@googlegroups.com. To view this discussion visit https://groups.google.com/d/msgid/golang-nuts/CAOyqgcWLfZ%3DYzYhDU4BQykU%2BKJaVauA-Tu8vn4UCXWXVX2QQwQ%40mail.gmail.com.
