Using underscore in return statements - a small convenience idea

Nick Craig-Wood

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Aug 23, 2023, 7:54:13 AM8/23/23

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// Sometimes you end up typing this having to return
// a value you made up but don't care about.
func f1() (int, error) {
return -1, errors.New("something went wrong")
}

// Or maybe like this with named return values.
func f2() (a int, err error) {
return a, errors.New("something went wrong")
}

// It would be nice if you could type this instead.
//
// The underscore being used here to return whatever is in
// the return slot when the return statement is executed.
func f() (a int, err error) {
return _, errors.New("something went wrong")
}

The last doesn't compile of course, it gives

cannot use _ as value or type

Being able to use _ seems like a nice convenience to me. What it actually returns is completely defined. And it would save us having to figure out types for stuff that you can't use `nil` for, eg `time.Time` is particularly annoying.

Thoughts?

Play: https://go.dev/play/p/TeNMV9zWemg

Brian Candler

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Aug 23, 2023, 9:51:37 AM8/23/23

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Something similar is in the pipeline: https://github.com/golang/go/issues/61372

When implemented, it will be spelled "zero" rather than "_"

As I understand it, you'll still need to say 0, "" or nil where those are available for the type in question. Therefore in the f1() example you gave, you'll still need

return 0, errors.New("something went wrong")

Nick Craig-Wood

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Aug 23, 2023, 10:10:19 AM8/23/23

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Ah ha! I thought there would be a related issue I couldn't find :-)

`zero` would remove most of the pain though IMHO `_` looks neater in the return statements!

Thanks for the pointer Brian.

Sean Liao

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Aug 23, 2023, 10:43:42 AM8/23/23

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