switchの挙動

sample.go

package main

import "fmt"

func main() {
  fmt.Println( "patternA" )
  patternA( 1 )
  fmt.Println( "patternB" )
  patternB( 1 )
}

func patternA( condition int ) {
  switch condition {
  case zero():
    fmt.Println( "0" )
  case one():
    fmt.Println( "1" )
  case two():
    fmt.Println( "2" )
  case three():
    fmt.Println( "3" )
  default:
    fmt.Println( "-" )
  }
}

func patternB( condition int ) {
  switch condition {
  case zero():
    fmt.Println( "0" )
  case one():
    fmt.Println( "1" )
    fallthrough
  case two():
    fmt.Println( "2" )
  case three():
    fmt.Println( "3" )
  default:
    fmt.Println( "-" )
  }
}

func zero() int {
  fmt.Println( "zero called" )
  return 0
}

func one() int {
  fmt.Println( "one called" )
  return 1
}

func two() int {
  fmt.Println( "two called" )
  return 2
}

func three() int {
  fmt.Println( "three called" )
  return 3
}