Just to quote the spec <https://go.dev/ref/spec#Struct_types> to clarify, perhaps:
> A field or method f of an embedded field in a struct x is called promoted if x.f is a legal selector that denotes that field or method f So there are two conditions for a method to be promoted: 1. it must be a legal selector (this is given for the example) and 2. that selector must denote the method. To check whether the selector `m.EqualName` (if `m` has type `meter` or `*meter`) denotes this field or method, we look up the rules for selector expressions <https://go.dev/ref/spec#Selectors> (emphasis mine): > For a value x of type T or *T where T is not a pointer or interface type, x.f denotes the field or method *at the shallowest depth* in T where there is such an f. If there is not exactly one f with shallowest depth, the selector expression is illegal. The field `meter.EqualName` has a more shallow depth than `meter.EqualName.EqualName`, thus `m.EqualName` denotes the field, not the method. Thus, the method is not promoted. Thus `meter` has no `EqualName` method, as the only way it could get one is by promotion. On Thu, 27 Feb 2025 at 22:46, Ian Lance Taylor <i...@golang.org> wrote: > On Thu, Feb 27, 2025 at 9:49 AM cpu...@gmail.com <cpui...@gmail.com> > wrote: > > > > Thanks Ian, you are of course correct- but I still don't get it. Thank > you for taking the time. > > > > > m.EqualName has to mean something. The Go language defines it as > > meaning the field in m's type, rather than the embedded method. > > > > Doesn't have meter an embedded field of type EqualName (the interface)? > > It has an embedded field whose name is EqualName and whose type is > EqualName. It's though the code said > > type meter struct { > EqualName EqualName > DifferentNamer DifferentNamer > } > > except that methods and fields of the embedded types are promoted. > > > > > Therefore, the type meter does not have a method EqualName. Therefore, > > the type meter does not implement the EqualName interface. > > > > meter doesn't. But impl's methods get promoted to meter- which happens > with different name: clearly the different name method has become promoted, > implements the different namer interface and is non-nil. > > > > I still don't fully understand why this doesn't work for equal name. If > impl's equal name method does get promoted it should implement the > interface since meter now as a equal name method. If it doesn't (due to > name conflict with the embedded equal name interface) where would still be > the embedded equal name interface (which might be nil but still existing)? > > As you say, if the EqualName method were promoted it would conflict > with the existing field of type EqualName. Therefore, it is not > promoted. Therefore, meter does not have a method named EqualName. It > has a field named EqualName instead. Therefore, meter does not > implement the interface EqualName. It doesn't have a method EqualName, > so there is no way that it could implement the interface EqualName. > > 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/CAOyqgcWf31G9fDT96qPfcPdnZhFXnYTvzpZpW_cYjAT_oAk0SA%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 visit https://groups.google.com/d/msgid/golang-nuts/CAEkBMfEXJSvew461xSLOODa%2B5zZPYk7USeV6va6x%3Dj%3DJqUUe%3Dg%40mail.gmail.com.
