On Mar 5, 2018, at 10:32 PM, Ian Lance Taylor <i...@golang.org> wrote:
>
> Go doesn't have anything like inheritance in C++. What you are
> calling the "true underlying type" simply doesn't exist in Go. Go has
> embedded fields, and methods of embedded fields are promoted to become
> methods of the outer type in which they are embedded. But the outer
> type does not inherit anything from the inner type, at least not if
> you are using the word "inherit" in the sense that it is used in C++.
> The promoted methods are still methods on the inner type, they are
> just accessible directly from the outer type.
>
> I think it's generally best to approach these problems in terms of how
> Go works, rather than trying to recreate C++ approaches in Go. Go
> doesn't work the way that C++ does.
>
> Ian
So why then does reflect.TypeOf(obj) return the “Outer” type in the example
code I posted, here:
func ArgFun(in InType) {
typ := reflect.TypeOf(in).Elem()
fmt.Printf("ArgFun on in tells the truth: %v\n", typ.Name())
}
https://play.golang.org/p/KmihXxU19Dd
I don’t think json.Marshal etc would work without this behavior..
Per the discussion here: https://github.com/golang/go/issues/22013 — it seems
like Go is rather unclear about exactly what level of C++-like inheritance it
wants to support. I don’t want to recreate any of that discussion here, but
I’ll just add a tiny vote for at least keeping the notion of embedding as it is
— don’t throw the baby out with the bathwater! The presence of interfaces and
the compositional model in Go is TONS better than C++’s rigid inheritance
constraints, but sometimes a simple inherit-and-extend model is just the right
thing, and it seems like it doesn’t add that much additional complexity to
support it. Maybe just need to add a bit of relevant docs in places to resolve
residual confusions, such as the one I encountered. Thanks for all your hard
work on creating this awesome language!
- Randy
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