01. Week 1 Exercise

Exercise

We will consider to porting Underscore in Javascript language to Go language

Most features

Some features such as IsEmpty, Last ... are missed in Go so we will try first

Helpers

IsEmpty

We can consider some of case:

• slice, map with len is zero
• string is ""
• boolean is false
• number is 0
• ...

So the simplest code could implemented is:

func IsEmpty(obj interface{}) bool {
  if obj == nil || obj == "" || obj == false || obj == 0 {
    return true
  }
  return false
}

func TestIsEmpty(t *testing.T) {
  table := []interface{}{false, "", 0, nil}
  for _, v := range table {
    expected := IsEmpty(v)
    if expected != true {
      t.Error("IsEmpty of \"", v, "\" is failed.")
    }
  }
}

Slice

More stricks of slice you can follow here

Last

For just reading the last element of a slice:

sl[len(sl)-1]

So we really don't need to reinvent the wheel for this, but in other way to think about readable code, we could consider this function

func Last(arr interface{}) interface{} {
  value := reflect.ValueOf(arr)

  return value.Index(value.Len() - 1).Interface()
}

func TestLast(t *testing.T) {
  arr := []int{1, 2, 3}
  v := Last(arr)
  var expected int
  expected = 3
  if v != expected {
    t.Error("Value should be ", expected)
  }
}