calculate函数，闭包与传函数

calculate.go

type operate func(x, y int) int

func calculate(x int, y int, op operate) (int, error) {
  if op == nil {
    return 0, error.New("no op")
  }
  return op(x, y), nil
}

var add = func (x, y int) int {
  return x + y
}

v, _ := operate(1, 2, add)
fmt.Printf(v)

closure.go

func genCalculator(op operate) operate {
  return func(x, y int) int {
    return op(x, y)
  }
}

add := genCalculator(func(x, y) int {
  return x + y
})
v := add(5, 6)
fmt.Println(v)