Bit flags in Go

bit_flags.go

package main

// explicite
const (
  SAY_NIL   = 0x00 // 0b00000000
  SAY_HELLO = 0x01 // 0b00000001
  SAY_FOO   = 0x02 // 0b00000010
  SAY_BYE   = 0x04 // 0b00000100
)

// simpler
const (
  A = 0x01 << iota
  B
  C
  D
  E
  F
  G
)

func SayStuff(mode int) {

  if mode&SAY_HELLO > 0 {
    println("HELLO")
  }

  if mode&SAY_FOO > 0 {
    println("FOO")
  }

  if mode&SAY_BYE > 0 {
    println("BYE")
  }
}

func main() {

  /* 
     SAY_HELLO  0b00000001 OR |
     SAY_FOO    0b00000010
     --------------------------
                0b00000011 OR |
     SAY_BYE    0b00000100
     --------------------------
                0b00000111


     mode       0b00000111 AND &
     SAY_HELLO  0b00000001
     --------------------------
                0b00000001 > 0
  */

  SayStuff(SAY_HELLO | SAY_FOO | SAY_BYE)
  SayStuff(SAY_NIL)

  // Example 2

  mode := A | C | G | E

  if mode&A != 0 {
    println("A is set")
  }

  if mode&B != 0 {
    println("B is set")
  }

  if mode&C != 0 {
    println("C is set")
  }

  if mode&D != 0 {
    println("D is set")
  }

  if mode&E != 0 {
    println("E is set")
  }

  if mode&F != 0 {
    println("F is set")
  }

  if mode&G != 0 {
    println("G is set")
  }
}