Hi, > However, I would like to point out that selector rule 3 states: > > As an exception, if the type of x is a defined pointer type and (*x).f is > a valid selector expression denoting a field (but not a method), then x.f > is shorthand for (**x).f.* > > The emphasis here is on "defined pointer type." In the code, *s is a > composite pointer literal type, not a defined pointer type. Therefore, I > believe this rule does not apply in this case. > As I mentioned on slack, the fact that this is not a defined pointer type means that is not the right rule to look at. Instead, you need to look at the first rule in the list.
> Furthermore, in selector rule 1, it only states that "x.f denotes the > field or method." The term "denotes" is somewhat ambiguous and does not > imply implicit pointer indirection. > I don't think this particular level of language-lawyering is useful. The spec is not a legal document or anything like that and should be read for intent. Writing `f().i` is allowed and well-defined, so the goal should be to justify *that* it is correct, not to come up with readings making it incorrect. A gracious reading of the spec here seems pretty clear. > 在2024年7月17日星期三 UTC+8 12:51:48<Ian Lance Taylor> 写道： > >> On Tue, Jul 16, 2024 at 9:29 PM 王旭东 <wxd...@gmail.com> wrote: >> > >> > Hi, I have a question about "addressable." >> > >> > The following code illustrates my question (see the comments): >> > https://go.dev/play/p/xpiPXuEqh0O?v=gotip >> > >> > >> > >> > I also posted question in the Gopher Slack channel, and @Axel Wagner >> provided a detailed explanation, suggesting that this might be a gap in the >> Go specification. >> > @Jason Phillips recommended that I ask this question in the GitHub >> issues and the golang-nuts mailing list. >> > >> > I really appreciate everyone’s help mentioned, but I still don’t have a >> clear conclusion. >> > >> > To simplify: my question is why the result of myfunReturnPointer() is >> addressable if we strictly follow the specification. >> >> >> In https://go.dev/ref/spec#Selectors the spec explains that if the >> type of x is a pointer, then the selector expression x.f is shorthand >> for (*x).f. That is the case in your playground example: the >> expression myfunReturnPointer().i is short for >> (*myfunReturnPointer()).i. The pointer indirection >> *myfunReturnPointer() is addressable according to >> https://go.dev/ref/spec#Address_operators. So this is a field >> selector of an addressable struct operand. >> >> 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 on the web visit > https://groups.google.com/d/msgid/golang-nuts/0fb5aa3e-4568-4520-bd42-ff01c1a2bd54n%40googlegroups.com > <https://groups.google.com/d/msgid/golang-nuts/0fb5aa3e-4568-4520-bd42-ff01c1a2bd54n%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/CAEkBMfH5K%2BKC7toieX30nWO8Umt7OnoYGwfd6h4FsTsW9uP3qQ%40mail.gmail.com.
