Naming receiving variables from a multiple return function

Question

Go allows for multiple named return values, but what about the receiving variables? Are they protected when return values are juggled around?

Let's say we start with this:

func foo() (i int, j int) {
   i = 1
   j = 2
   return
}

a, b := foo()

Now what if some other coder comes by and makes the following change to foo's definition:

func foo() (j int, i int) {

my calling function is invalidated. Is it, then, possible to name the returned values from the calling side as well. For instance, if I called it like this:

(a:i, b:j) := foo()

then I would be attaching them to the named return values, rather than assigning them in the order they are returned.

So, is there a way to solve that problem?

*"Is it, then, possible to name the returned values from the calling side as well."* No, it isn't possible. *"So, is there a way to solve that problem?"* the only thing I can think of are unit tests and documentation. — mkopriva, Jul 19 '19 at 17:14
Related / possible duplicate of [Initialize function fields](https://stackoverflow.com/questions/48153929/initialize-function-fields/48154019?r=SearchResults#48154019). — icza, Jul 19 '19 at 17:20

score 1 · Accepted Answer · answered Jul 19 '19 at 17:15

This is no different than rearranging the input parameters. As a rule, don't do that unless you intend to make a breaking change. But if you want to deal with things by name rather than position, you want a struct. For example, you can use anonymous structs:

func foo() struct {
    i int
    j int
} {
    return struct {
        i int
        j int
    }{1, 2}
}

func main() {
    result := foo()
    fmt.Println(result.i, result.j)
}

Of course you can also name the struct if you used it in other places, but there's no need if you just want to name the fields.

Naming receiving variables from a multiple return function

1 Answers1