Nope. Your solution doesn't work either: https://go.dev/play/p/DSik2kJ-gg4 (it doesn't crash, just falsely returns 'false').
What I'm trying to check is pretty straightforward: do I get the nil value passed to a function. All types are completely valid, the structure is correctly cast to the base interface type and its methods can be safely called: https://go.dev/play/p/xseNiCSB0uA I don't see anything "uninteresting" in that. In a real program the interface is simply passed through an intermediate function, so I can't use an exact type. That's a stupid part of the language and there's no good justification why this hasn't been yet fixed. On Wednesday, March 16, 2022 at 10:36:48 AM UTC-7 axel.wa...@googlemail.com wrote: > On Wed, Mar 16, 2022 at 6:21 PM Alex Besogonov <alex.be...@gmail.com> > wrote: > >> I'm trying to solve the eternal "interface == nil" problem and I can't >> find a solution in this case: https://go.dev/play/p/DSik2kJ-gg4 >> > > ISTM that you are discovering why this check just is not an interesting > check to make in the first place. > > There is no meaning you can assign to "is the dynamic value of a non-nil > interface nil", as `nil` might not even be a valid value for its dynamic > type. It's also not a *helpful* check, because even non-nil pointers can > cause a panic, if you call an associated method on them. > > You *can* write a check to see if a value contains a pointer relatively > easily using reflect: > https://go.dev/play/p/dDHp7KnoHHS > But it's not a very useful check, unless you specifically want to work > further with the pointer using reflect (e.g. how json.Unmarshal stores a > value in a pointer). > > >> >> It looks like casting to the base pointer type confuses the reflection >> package. Is there a way to solve this? >> >> PS: PLEASE do add "nilptr" to the language proper. >> >> -- >> 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/469b88b2-6d64-4bcd-8b92-18f9781c4fd3n%40googlegroups.com >> >> <https://groups.google.com/d/msgid/golang-nuts/469b88b2-6d64-4bcd-8b92-18f9781c4fd3n%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/75f9517f-c6ea-4a93-8c88-d1293b5c8c0en%40googlegroups.com.
