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go

Built-in helper for "Must" pattern in Go

Is there a more built-in wrapper to make a function that returns (X, error) successfully execute or abort, like regexp.MustCompile?

I'm talking about something like this, but more "built-in".

Solution

  • Since Go 1.18 we can define typed Must instead of interface{}:

    func Must[T any](obj T, err error) T {
    if err != nil {
        panic(err)
    }
    return obj
}

    How to use: https://go.dev/play/p/ajQAjfro0HG

    func success() (int, error) {
    return 0, nil
}

func fail() (int, error) {
    return -1, fmt.Errorf("Failed")
}

func main() {
    n1 := Must(success())
    fmt.Println(n1)
    var n2 int = Must(fail())
    fmt.Println(n2)
}

    Must fails inside main, when fail() returns non-nil error

    You can even define Mustn for more than 1 return parameter, e.g.

    func Must2[T1 any, T2 any](obj1 T1, obj2 T2, err error) (T1, T2) {
    if err != nil {
        panic(err)
    }
    return obj1, obj2
}