Golang pointers

Question

I am currently learning to program with Go language. I am having some difficulties understanding Go pointers (and my C/C++ is far away now...). In the Tour of Go #52 (http:/

Answer 1

There are two different rules of the Go language used by your examples:

1. It is possible to derive a method with a pointer receiver from a method with a value receiver. Thus func (v Vertex) Abs() float64 will automatically generate an additional method implementation:

   func (v Vertex) Abs() float64 { return math.Sqrt(v.X*v.X+v.Y*v.Y) }
   func (v *Vertex) Abs() float64 { return Vertex.Abs(*v) }  // GENERATED METHOD
   

   The compiler will automatically find the generated method:

   v := &Vertex{3, 4}
   v.Abs()  // calls the generated method
   

2. Go can automatically take the address of a variable. In the following example:

   func (v *Vertex) Abs() float64 { return math.Sqrt(v.X*v.X+v.Y*v.Y) }
   func main() {
       v := Vertex{3, 4}
       v.Abs()
   }
   

   the expression v.Abs() is equivalent to the following code:

   vp := &v
   vp.Abs()