Then just use pointers (see lines 45+): https://play.golang.org/p/vl47WDHOdN
On Mon, Nov 7, 2016 at 4:50 PM Kaylen Wheeler <kfjwhee...@gmail.com> wrote: I want pointers because I want most components to be structs, and I want the ability to modify the fields in those structs. On Monday, 7 November 2016 16:46:17 UTC-8, freeformz wrote: Why do you want to use pointers? On Mon, Nov 7, 2016 at 4:42 PM Kaylen Wheeler <kfjwh...@gmail.com> wrote: Thanks for the "basic pattern" example here. There's one little modification I'm wondering about. Can this line: rv.Elem().Set(m[rv.Type()]) be changed to this? rv.Elem().Set(*&*m[rv.Type()]) If so, how can we check that the input value is a pointer to a pointer. Or alternatively, is it better that the values in m should be pointers? On Monday, 7 November 2016 16:01:53 UTC-8, adon...@google.com wrote: On Monday, 7 November 2016 17:55:57 UTC-5, Kaylen Wheeler wrote: I'm trying to find a typesafe way to access a type-indexed map of components. This map can contain objects of any type, and the keys are reflect.Type. One strategy I thought may work would be to pass a pointer to a pointer as an out-var. Using reflection to determine the pointer's type, it could be populated with a corresponding value. For instance, if we did something like this: c := ComponentCollection{} c.addComponent(123) // Add an int component var p : *int c.getComponent(&p) In this case, p would point to the int component of c. That's wht the 2 levels of indirection are necessary: it's an out-var to a pointer. Does that make sense? Here's the basic pattern: var m = make(map[reflect.Type]reflect.Value) func addComponent(x interface{}) { v := reflect.ValueOf(x) m[v.Type(x)] = v } func getComponent(ptr interface{}) { rv := reflect.ValueOf(ptr) if rv.Kind() != reflect.Pointer { panic("not a pointer") } rv.Elem().Set(m[rv.Type()]) } -- 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. 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.