How to subclass in Go

In C I can do something like this

struct Point {
  int x,y;
}

struct Circle {
  struct Point p;       // must be first!
  int rad;
}

void move(struct Point *p,int dx,int dy) {
    ....
}

struct Circle c = .....;
move( (struct Point*)&c,1,2);

Using this approach, I can pass any struct(Circle,Rectangle,etc) that has struct Point as first member.
How can I do the same in google go?

Actually, there's a simpler way to do it, which is more similar to the OP's example:

type Point struct {
	x, y int
}

func (p *Point) Move(dx, dy int) {
	p.x += dx
	p.y += dy
}

type Circle struct {
	*Point // embedding Point in Circle
	rad int
}

// Circle now implicitly has the "Move" method
c := &Circle{&Point{0, 0}, 5}
c.Move(7, 3)

Also notice that Circle would also fulfill the Mover interface that PeterSO posted.

http://golang.org/doc/effective_go.html#embedding

> Although Go has types and methods and
> allows an object-oriented style of
> programming, there is no type
> hierarchy. The concept of “interface”
> in Go provides a different approach
> that we believe is easy to use and in
> some ways more general. There are also
> ways to embed types in other types to
> provide something analogous—but not
> identical—to subclassing. Is Go an
> object-oriented language?, FAQ.

For example,

package main

import "fmt"

type Mover interface {
	Move(x, y int)
}

type Point struct {
	x, y int
}

type Circle struct {
	point Point
	rad   int
}

func (c *Circle) Move(x, y int) {
	c.point.x = x
	c.point.y = y
}

type Square struct {
	diagonal int
	point    Point
}

func (s *Square) Move(x, y int) {
	s.point.x = x
	s.point.y = y
}

func main() {
	var m Mover
	m = &Circle{point: Point{1, 2}}
	m.Move(3, 4)
	fmt.Println(m)
	m = &Square{3, Point{1, 2}}
	m.Move(4, 5)
	fmt.Println(m)
}