Looking for reasonable stack implementation in golang?

Issue

So far my naive approach is

type stack []int

func (s *stack) Push(v int) {
    *s = append(*s, v)
}

func (s *stack) Pop() int {
    res:=(*s)[len(*s)-1]
    *s=(*s)[:len(*s)-1]
    return res
}

it works – playground, but looks ugly and has too much dereferencing. Can I do better?

Solution

It’s a matter of style and personal taste, your code is fine (apart from not being thread safe and panicking if you pop from an empty stack). To simplify it a bit you can work with value methods and return the stack itself, it’s slightly more elegant to some tastes. i.e.

type stack []int

func (s stack) Push(v int) stack {
    return append(s, v)
}

func (s stack) Pop() (stack, int) {
    // FIXME: What do we do if the stack is empty, though?

    l := len(s)
    return  s[:l-1], s[l-1]
}


func main(){
    s := make(stack,0)
    s = s.Push(1)
    s = s.Push(2)
    s = s.Push(3)

    s, p := s.Pop()
    fmt.Println(p)

}

Another approach is to wrap it in a struct, so you can also easily add a mutex to avoid race conditions, etc. something like:

type stack struct {
     lock sync.Mutex // you don't have to do this if you don't want thread safety
     s []int
}

func NewStack() *stack {
    return &stack {sync.Mutex{}, make([]int,0), }
}

func (s *stack) Push(v int) {
    s.lock.Lock()
    defer s.lock.Unlock()

    s.s = append(s.s, v)
}

func (s *stack) Pop() (int, error) {
    s.lock.Lock()
    defer s.lock.Unlock()


    l := len(s.s)
    if l == 0 {
        return 0, errors.New("Empty Stack")
    }

    res := s.s[l-1]
    s.s = s.s[:l-1]
    return res, nil
}


func main(){
    s := NewStack()
    s.Push(1)
    s.Push(2)
    s.Push(3)
    fmt.Println(s.Pop())
    fmt.Println(s.Pop())
    fmt.Println(s.Pop())
}

Answered By – Not_a_Golfer

Answer Checked By – Marilyn (GoLangFix Volunteer)

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