> The reflect code panics, because you are comparing a struct value to nil. >> Struct values can not be nil. >> >> No. I’m comparing AN INTERFACE, not a struct. >> > You are using `reflect` to inspect the dynamic value of that interface. > That dynamic value is a struct. > No. It should be a POINTER to a struct, which would have been fine. Instead Go's reflection incorrectly latches on the type of the embedding structure.
> The interface’s provenance is _through_ a struct that has an embedded >> pointer, but this should not matter to the code that accepts the interface. >> > I completely agree with this. That's why it is so important not to store > invalid values in an interface. The code using that interface has no > reasonable way to check if the value is valid. So it has to rely on the > caller to only provide valid implementations. > The code is NOT using anything incorrect. The interface is obtained through a pointer to a struct, which is completely valid. The only problem is that this pointer is embedded inside a struct. If you rewrite the code to use a named field, it would work. This means that the language behaves differently depending on a field having a name. > > But really, the solution here is not to "check better". It's to not store > invalid implementations of an interface in the interface. > > I gave you the real example, somewhat simplified. > Then this is the real example with the fix applied: > https://go.dev/play/p/04H1KenHjRV > The real example would look like this: https://go.dev/play/p/mwUfh4_RBUU - you do see why it's a tad problematic? -- 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/58d5770b-4888-4980-8f9e-c96310d57490n%40googlegroups.com.
