如何在golang中返回int或nil？

Question

I'm a java developer and I am learning Go. I'm writing simple 'pop' operation for a LIFO stack. The question is with the return value when there are no values in the stack. In java, I'm able to return a wrapper(Integer) in the positive case and null when there are no values. It's natural from my perspective.

How can I do something similar in Go? Are there any struct wrappers for primitives? Do I need to return two values(the second will indicate error code)? Or do I need to throw an exception?

Here's how it looks for now:

func (s *stack) Pop() (int, bool)  {
    if s.size == 0 {
        return 0, true
    }
    s.size--
    val := s.stack[s.size]
    return val, false
}

Is it good style?

Answer 1

Since a number can't be nil, you can't return nil for integer, unless you define the return value as a pointer. The idiomatic solution in Go is by defining your method to return more than one values, e.g.

func (s *stack) Pop() (int, bool) {
    //does not exists
    if ... {
        return 0, false
    }

    //...

    //v is the integer value
    return v, true
}

Then somewhere you can call Pop as

s := &stack{}
if v, ok := s.Pop(); ok {
    //the value exists
}

Take a look at comma, ok idiom.