How do I reverse a slice in go?

Question

How do I reverse an arbitrary slice ([]interface{}) in Go? I\'d rather not have to write Less and Swap to use sort.Reverse

Answer 1

There is not a simple, built-in for reversing a slice of interface{}. You can write a for loop to do it:

for i, j := 0, len(s)-1; i < j; i, j = i+1, j-1 {
    s[i], s[j] = s[j], s[i]
}

Use the reflect.Swapper function introduced in Go 1.8 to write a generic reversing function:

func reverseAny(s interface{}) {
    n := reflect.ValueOf(s).Len()
    swap := reflect.Swapper(s)
    for i, j := 0, n-1; i < j; i, j = i+1, j-1 {
        swap(i, j)
    }
}

playground example