That is not really true though, as I can declare a method that take a pointer receiver and mutate through it, but the caller can pass a struct which it thinks can not be mutated.
https://play.golang.org/p/Abf4VX9kUTR Go isn’t type safe by stating that methods cannot mutate structs. Any reader of the above code would think that couldn’t work, unless they inspected the source to find a pointer receiver. > On Nov 19, 2018, at 3:28 PM, Axel Wagner <axel.wagner...@googlemail.com> > wrote: > > The restriction has nothing to do with heaps (in fact, the Go language > (i.e. the spec) doesn't even have a concept of a "heap"). It's a > type-safety requirement. If you pass in a value, it can't be mutated, > full-stop. Reflect shouldn't allow you to bypass type-safety - only > "unsafe" can do that, hence the name. >> On Mon, Nov 19, 2018 at 9:51 PM Robert Engels <reng...@ix.netcom.com> wrote: >> >> Interesting. I guess that makes sense. But you would think that if using a >> reflection call should force the compiler to heap allocate , then no reason >> for the restriction. >> >>> On Nov 19, 2018, at 2:33 PM, Ian Denhardt <i...@zenhack.net> wrote: >>> >>> Quoting Robert Engels (2018-11-19 15:13:53) >>>> But isn’t that just for safety. Meaning the unmarshall could use it as a >>>> pointer via reflection and mutate it (but that is probably not what the >>>> caller expects in Go) ? >>> >>> No, see: >>> >>> https://play.golang.org/p/MyF0Dx87-1j >>> >>> If you pass in &foo instead and insert the appropriate call to >>> value.Elem(), it works. >>> >>> -- >>> 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. >>> For more options, visit https://groups.google.com/d/optout. >> >> -- >> 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. >> For more options, visit https://groups.google.com/d/optout. -- 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. For more options, visit https://groups.google.com/d/optout.
