Go接口返回类型

Question

I have an interface like this:

type ViewInterface interface{
    Init() View
}

type View struct{
    Width  int
    Height int
}

So I create a new type from View

type MainView View

func (m MainView) Init() MainView{
 return MainView{
   Width:10,
   Height:10,
 }
}

then I pass the MainView to the following method:

func Render(views ...ViewInterface){
  for _, view := range views {
     v := view.Init()
  }
}

func main() {
  Render(MainView{})
}

But I get this error:

cannot use MainView literal (type MainView) as type ViewInterface in argument to Render: MainView does not implement ViewInterface (wrong type for Init method)
have Init() MainView
want Init() View

Why MianView is not same as View? what is the right way to solve this problem?

thanks

Answer 1

GO has different inheritance model comparing to mainstream languages like Java and C#.

Why MianView is not same as View?

Because they are defined differently.

Init function of MainView returns MainView while interface requires to return View.

Signature of Init method looks strange, it requires instance of structure because it is structure method and returns new instance of the same structure type.

Try to design interface around logic of your structures instead of their construction/lifetime:

type ViewInterface interface{
    Render()
}

type MainView View

func (m MainView) Render() {
  // do something
}

type AnotherView

func (m AnotherView) Render() {
  // do something else
}

func Render(views ...ViewInterface){
  for _, view := range views {
     view.Render()
  }
}