# better way to express a function in Go (Struct methods)

## Issue

This is a function to traverse an array of Points. A Point is a struct with elements x and y of type int. The traverse function is called from another function with a value of dir. The if check at the beginning of the loop can be avoided because the dir value, once the function is called, does not change. Is there a better way to express this logic in Go? The struct method returns a Point. I have provided one example of the struct method.

``````type Point struct {
x int
y int
}

func (p Point) next_row() Point {
nearby := Point{p.x + 1, p.y}
return nearby
}

func trv_point(p Point, p_list []Point, dir string) int {
seg_count := 0
var nearby Point
for {
if dir == "up" {
nearby = p.prev_row()
}
if dir == "down" {
nearby = p.next_row()
}
if dir == "left" {
nearby = p.prev_col()
}
if dir == "right" {
nearby = p.next_col()
}

if !check_point_in_slice(p_list, nearby) {
break
}
seg_count++
p = nearby

}
return seg_count
}

``````

## Solution

Because the `dir` is not change here, those `if` statements are redundent, also you should use `if-else` statments for this case because just one of the ["up", "down", "left", "right"] could happened.
First look to this example:

``````type Point struct {
x int
y int
}

func (p *Point) next_row() {
p.x += 1
}

func main() {
p := Point{0, 0}
f := p.next_row

for i := 0; i < 2; i++ {
fmt.Println(p)
f()
}
fmt.Println(p)
}
``````

the output will be:

``````{0 0}
{1 0}
{2 0}
``````

Here we change the receiver from `(p Point)` to `(p *Point)` because we want to save the effects on `x` and `y`.
By this assumption we could rewrite as:

``````type Point struct {
x int
y int
}

func (p *Point) next_row() {
p.x += 1
}

func get_move(dir string) func() {
var f func()
switch dir {
case "up":
f = p.prev_row
case "down":
f = p.next_row
case "left":
f = p.prev_col
case "right":
f = p.next_col
}
return f
}

func trv_point(p Point, p_list []Point, dir string) int {
seg_count := 0
var nearby Point
f := get_move(dir)
for check_point_in_slice(p_list, p) {
f()
seg_count++
}
return seg_count
}
``````

Answered By – S4eed3sm

Answer Checked By – Gilberto Lyons (GoLangFix Admin)