Overview

IOTA provides an automated way to create an enum in Golang. Let’s see an example.

Example

package main
import "fmt"
type Size uint8
const (
small Size = iota
medium
large
extraLarge
)
func main() {
fmt.Println(small)
fmt.Println(medium)
fmt.Println(large)
fmt.Println(extraLarge)
}

Output

0
1
2
3

In above program we created a new type

type Size uint8

Then we declared some const of type Size. The first constant small is set to iota so it will be set to zero

small Size = iota

That’s why

fmt.Println(small) >> outputs 0
fmt.Println(medium) >> outputs 1
fmt.Println(large) >> outputs 2
fmt.Println(extraLarge) >> outputs 3

Without IOTA we had to explicitly set the values of each of the enum value

package main
import "fmt"
type Size uint8
const (
small Size = 0
medium Size = 1
large Size = 2
extraLarge Size = 3
)
func main() {
fmt.Println(small)
fmt.Println(medium)
fmt.Println(large)
fmt.Println(extraLarge)
}

Output

0
1
2
3

We can also define a method toString on Size type to print the exact value of enum . See below program

package main
import "fmt"
type Size int
const (
small = Size(iota)
medium
large
extraLarge
)
func main() {
var m Size = 1
m.toString()
}
func (s Size) toString() {
switch s {
case small:
fmt.Println("Small")
case medium:
fmt.Println("Medium")
case large:
fmt.Println("Large")
case extraLarge:
fmt.Println("Extra Large")
default:
fmt.Println("Invalid Size entry")
}
}

Output

medium

We have defined a toString method for the Size type. It can be used to the print the string value of the constant of Size type.