CODEWITHSUNDEEP
go
user187676
user187676

Reputation:

Slice storage reference in Go

In the Go library source you often see that a slice is passed by creating a new slice storage reference like so

method(s[:])

What's the benefit of this, compared to just passing the original slice?

method(s)

Upvotes: 5

Views: 213

Answers (2)

gprasant
gprasant

Reputation: 16023

The only case where you would see code like this is when s is an array, and you want to pass as a parameter to a function that takes a slice as its input. Take the following code. 

package main
func main() {
    x := [...]int{1, 2, 3, 4, 5}
    someFunction(x)   // type mismatch error : expecting [] int, passed [5] int 
    someFunction(x[:])// no error   
}

func someFunction(input []int){
    // use input 
}

The thing to note here is that [] int and [5] int are entirely different types.

Upvotes: 1

zzzz
zzzz

Reputation: 91243

The s[:] construct is normally used only to create a new slice referencing an existing array, not for "passing the original slice".

If s[:] is really used somewhere in the stdlib and s is a slice than it could be e.g. a refactoring leftover. Please report such place if known to you on the Go issue tracker.

Upvotes: 6

Related Questions