Go — how to handle common fields between struct types

Question

If I have two types:

type A struct {
      X int
      Y int
}

type B struct {
      X int
      Y int
      Z int 
}

Is there any way to achieve the following without needing two methods, given that both access identically-named fields and return the sum of them?

func (a *A) Sum() int {
     return a.X + a.Y
}

func (b *B) Sum() int {
     return b.X + b.Y
}

Of course, were X and Y methods, I could define an interface containing these two methods. Is there an analogue for fields?

Answer 1

Embed A in B.

type A struct {
      X int
      Y int
}

func (a *A) Sum() int {
     return a.X + a.Y
}

type B struct {
      *A
      Z int 
}

a := &A{1,2}
b := &B{&A{3,4},5}

fmt.Println(a.Sum(), b.Sum()) // 3 7

http://play.golang.org/p/fjT9c-m_Lj

But no, there's no interface for fields. Only methods.