缺少对数组常量的支持的解决方法？ [重复]

Question

This question already has an answer here:

• Declare a constant array 4 answers

Go doesn't have array constants.

My application receives messages containing several types of numeric codes which I need to display as phrases.

If array contants existed I could do something like:

func foo() {
   ...
   fmt.Println(facename[f])
   ...
}
const facename [...]string = "top", "bottom", "left", "right", "front", "back"

But of course there's no way to do this. The first way around this that occurs to me, and maybe a reasonable efficient one is to use a switch

func foo() {
   ...
   name := "unknown"
   switch f {
   case 0:
      name = "top"
   case 1:
      name = "bottom"
   case 2:
      name = "left"
   case 3:
      name = "right"
   case 4:
      name = "front"
   case 5:
      name = "back"
   }
   fmt.Println(name)
   ...
}

The above is rather tedious if the number of values gets to be twenty or more.

It seems the most concise way is something like

func foo() {
   ...
   fmt.Println(strings.Split(facenames,",")[f])
   ...
}
const facenames = "top,bottom,left,right,front,back"

I will also have to check that the index is in range of course. Although efficiency isn't a concern at the moment, it bugs me that I'm using strings.Split() more than I want to.

Is there another way that is either idiomatic or both concise and efficient?

</div>

Answer 1

The idiomatic approach is to use a package level variable:

var facename = []string{"top", "bottom", "left", "right", "front", "back"}

func foo() {
    // ...
    fmt.Println(facename[f])
    // ...
}

It's also idiomatic to use a slice instead of an array in this situation.