Today I learned (revisted after a long while) how to make a copy of a slice in Go using the in-built copy function. The process is still cumbersome (compared to python) but that’s the trade-off you gotta make.

This is because slices in Go are passed by reference. That means you can’t copy by value using a := b.

Instead, you have to do this

copyArr := make([]int, len(arr))
copy(copyArr, arr)

Perhaps, if you’re doing this enough number of times in your go program, it ought to be useful to just build a helper function and use that everytime.

func copyIntSlice(arr []int) []int {
    copyArr := make([]int, len(arr))
    copy(copyArr, arr)
    return copyArr
}

If you want to make it data-type agnostic and you’re working with go1.18+, then you can use generics,

func copySlice[T any](arr []T) []T {
	copyArr := make([]T, len(arr))
	copy(copyArr, arr)
	return copyArr
}

This trick could help programmers gain back a ton of time in dev-loops. Hope you found this helpful!

👋 ⸻ @TnvMadhav