Answers for "enum in golang"

enum in golang

type ByteSize float64

const (
	_           = iota // ignore first value by assigning to blank identifier
	KB ByteSize = 1 << (10 * iota)
	MB
	GB
	TB
	PB
	EB
	ZB
	YB
)

// String changes the default print
func (b ByteSize) String() string {
	switch {
	case b >= YB:
		return fmt.Sprintf("%.2fYB", b/YB)
	case b >= ZB:
		return fmt.Sprintf("%.2fZB", b/ZB)
	case b >= EB:
		return fmt.Sprintf("%.2fEB", b/EB)
	case b >= PB:
		return fmt.Sprintf("%.2fPB", b/PB)
	case b >= TB:
		return fmt.Sprintf("%.2fTB", b/TB)
	case b >= GB:
		return fmt.Sprintf("%.2fGB", b/GB)
	case b >= MB:
		return fmt.Sprintf("%.2fMB", b/MB)
	case b >= KB:
		return fmt.Sprintf("%.2fKB", b/KB)
	}
	return fmt.Sprintf("%.2fB", b)
}

func main() {
  fmt.Println(ByteSize(1e13))	// output: 9.09TB
}

/**
Constant and Enum in Golang:
	- They are created at compile time, even when defined as 
      locals in functions, and can only be numbers, 
      characters (runes), strings or booleans.
	- Because of the compile-time restriction, the expressions 
      that define them must be constant expressions, evaluatable
      by the compiler. For instance, 1<<3 is a constant expression,
      while math.Sin(math.Pi/4) is not because the function call 
      to math.Sin needs to happen at run time.
	- In Go, enumerated constants are created using the iota 
      enumerator.
	- Since iota can be part of an expression and expressions 
      can be implicitly repeated, it is easy to build intricate
      sets of values.
**/