I read that and I genuinely do not understand why interfaces now mean two distinct incompatible things. I think this is going to confuse a lot of people.
On Wed, Dec 15, 2021 at 11:09 AM Jason Phillips <jasonryanphill...@gmail.com> wrote: > As to _why_ this is the case, the generics proposal has a section about > that: > > https://go.googlesource.com/proposal/+/refs/heads/master/design/43651-type-parameters.md#permitting-constraints-as-ordinary-interface-types > > On Wednesday, December 15, 2021 at 11:05:36 AM UTC-5 Jason Phillips wrote: > >> @Leonard, type constraints can only be used as type parameters, using >> them as normal interfaces is currently not allowed. See the notes in the >> draft release notes[1] or the draft 1.18 spec[2]. >> >> > Such interfaces may only be used as type constraints. >> >> > Interfaces that contain non-interface types, terms of the form ~T, or >> unions may only be used as type constraints, or as elements of other >> interfaces used as constraints. They cannot be the types of values or >> variables, or components of other, non-interface types. >> >> @Kurtis, that issue is about embedded fields (fields without explicit >> field names) that use type parameters. >> >> [1] - https://tip.golang.org/doc/go1.18 >> [2] - https://tip.golang.org/ref/spec#Interface_types >> >> On Wednesday, December 15, 2021 at 10:47:20 AM UTC-5 kra...@skepticism.us >> wrote: >> >>> This was asked 15 hours ago in the thread with the subject line "Go 1.18 >>> beta1: Embedding Type Parameter in struct definition is an error". :-) >>> >>> See https://golang.org/issue/49030. >>> >>> On Wed, Dec 15, 2021 at 3:24 AM Leonard Mittmann <leonard....@gmail.com> >>> wrote: >>> >>>> I just learned that type constraints, which are defined as interfaces >>>> are actually not usable in all the places "normal" interfaces can be used >>>> in. E.g., why can a constraint interface not be uses as a struct type? >>>> >>>> Let's say I have the func `func Smallest[T constraints.Ordered](s []T) >>>> T`. How do I write a table test for this func? Intuitively one would >>>> try to store tests like this: >>>> >>>> tests := []struct { >>>> Arr: []constraints.Ordered >>>> Want: constraints.Ordered >>>> }{...} >>>> >>>> But this is not permitted. Am I missing something why this behavior is >>>> should be considered good? If a type constraint is nothing like an >>>> interface... okay, but why call it interface then? >>>> >>>> -- >>>> 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...@googlegroups.com. >>>> To view this discussion on the web visit >>>> https://groups.google.com/d/msgid/golang-nuts/53df110e-8f34-490a-9b77-610dacffdbcfn%40googlegroups.com >>>> <https://groups.google.com/d/msgid/golang-nuts/53df110e-8f34-490a-9b77-610dacffdbcfn%40googlegroups.com?utm_medium=email&utm_source=footer> >>>> . >>>> >>> >>> >>> -- >>> Kurtis Rader >>> Caretaker of the exceptional canines Junior and Hank >>> >> -- > 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/0ae9aed8-72d4-42a2-acf0-16d0bd6b08ecn%40googlegroups.com > <https://groups.google.com/d/msgid/golang-nuts/0ae9aed8-72d4-42a2-acf0-16d0bd6b08ecn%40googlegroups.com?utm_medium=email&utm_source=footer> > . > -- 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/CANGiwgY2%2B-xEBzezeh-D_0dv2hQXreWLsiXoOSP%2Bw-LUV%3DkVaw%40mail.gmail.com.
