How do I (succinctly) remove the first element from a slice in Go?

modocache picture modocache · May 8, 2014 · Viewed 27.2k times · Source

I've built a simple queue in Go. It uses an internal slice to keep track of its elements. Elements are pushed onto the queue by appending to the slice. I'd like to implement .Pop() by removing the first element in elements.

In many other languages, "popping" the first element of a list is a one-liner, which leads me to believe my implementation below is sloppy and verbose. Is there a better way?

type Queue struct {
    elements []interface{}
}

func (queue *Queue) Push(element interface{}) {
    queue.elements = append(queue.elements, element)
}

func (queue *Queue) Pop() interface{} {
    element := queue.elements[0]
    if len(queue.elements) > 1 {
        queue.elements = queue.elements[1:]
    } else {
        queue.elements = make([]interface{}, 0)
    }
    return element
}

Please note that I wish for the Queue to panic if len(queue.elements) == 0. It's not an oversight that I don't check the bounds.

Answer

Everton picture Everton · May 8, 2014

Did you try these?

Pop from queue

x, a = a[0], a[1:]

Pop from stack

x, a = a[len(a)-1], a[:len(a)-1]

Push

a = append(a, x)

From: https://code.google.com/p/go-wiki/wiki/SliceTricks