errors

README

errors (github.com/pkg/errors) example

Error handling using non-standard github.com/pkg/errors package.

Refer to the github.com/pkg/errors package for more info.

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HANDLE ERRORS

Go doesn’t have exceptions, so it doesn’t have try, catch or anything similar. So how do we handle errors? With Multiple return values.

MULTIPLE RETURN VALUES

As an example,

func a(x int) (int, error) {
    if x == 42 {
        // Make your error
        return -1, errors.New("can't work with 42")
    }
    return x + 3, nil
}

func main() {
    //MULTIPLE RETURN VALUES
    r, err := b(42)
    if err != nil {
        // Handle the error
        fmt.Printf("Error is %+v\n", err)
        log.Fatal("ERROR:", err)
    }
    // Continue
    fmt.Println("Returned", r)
}

The beauty of the github.com/pkg/errors package is that it traces the error back to the source. That's why we use fmt.Printf("Error is %+v\n", err).

Since you check errors a lot, make an error checker function,

func checkErr(err error) {
    if err != nil {
        fmt.Printf("Error is %+v\n", err)
        log.Fatal("ERROR:", err)
    }
}

func main() {
    //MULTIPLE RETURN VALUES (Simpler form)
    r, err = b(42)
    checkErr(err)
    fmt.Println("Returned", r)
}

RUN

To get,

go get -u -v github.com/pkg/errors

Run,

go run errors.go

Notice how it traces the error back to your original function.