Is there a way to cast interface to embedded type?

[Christopher C]

I have a base struct that implements an interface. There are multiple other structs that embed this base struct.  I would like to pass the an interface into a function that can cast it as the base struct and call some functions tied to the base struct.

 

Something like this...

https://go.dev/play/p/DUzXr31s8Pn

[burak serdar]

On Fri, Feb 9, 2024 at 1:37 PM Christopher C
<crotty.ch...@gmail.com> wrote:
>
> I have a base struct that implements an interface. There are multiple other structs that embed this base struct. I would like to pass the an interface into a function that can cast it as the base struct and call some functions tied to the base struct.

No, because type assertion tests the type of the object contained in
an interface, and that object is not the base object.

However, you can put whatever functions you are planning to call in
that base object into another interface, and call that:

type Base struct {...}

func (Base) A() {}
func (Base) B() {}

type HasA interface {
A()
}

func f(in HasA) {
type hasB interface {
B()
}
b,ok:=in.(hasB)
if ok {
b.B()

}
}




>
> Something like this...
> https://go.dev/play/p/DUzXr31s8Pn
>

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[Mike Schinkel]

You can't cast like in your example, but you can create an interface — call is `Baser` using idiomatic interface naming to identify the `Base` type which will have an empty `Base()` method — and then type assert to it after which, if it succeeds you can type assert to `*Base`, like so:

https://go.dev/play/p/-gcKGf4_AFg

Hope this helps.

-Mike

[Christopher C]

Thanks to both of you. I'll try out your suggestions.