methods

// Methods are allow us to create functions on types

type Coord struct { X, Y int32 }

// They require a receiver argument between the keyword and name
// Define a function that expects a Coord type named c, is named Combine, and will return a 32 bit int
func (c Coord) Combine() int32 {
    return c.X + c.Y
}
...
a := Coord{5, 2}
b := a.Combine()    // 7

// We can pass in a pointer of our type to operate directly upon it
func (c *Coord) Double() {
    c.X = c.X * 2
    c.Y = c.Y * 2
}
...
a := Coord(5, 2}
a.Double()         // {10 4}

// We can't overload primitives
// We can, however, extend them
type NewFloat float64
func (nf NewFloat) Double() NewFloat {
    return nf * NewFloat(2)
}
...
f := NewFloat(5)
f = f.Double() // 10



// For comparison
type Coord struct{ X, Y int32 }

func (c *Coord) Double() {
    c.X = c.X * 2
    c.Y = c.Y * 2
}

func Double(c *Coord) {
    c.X = c.X * 2
    c.Y = c.Y * 2
}
...
c := Coord{5, 3}
c.Double()
// Is the same as
Double(&c)