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错误 Errors

Golang 中的错误处理方式会让我们自动考虑如何处理错误情况。

func main() {
    user, err := getUser()
    if err != nil {
        fmt.Println(err)
        return
    }

    profile, err := getUserProfile(user.ID)
    if err != nil {
        fmt.Prinln(err)
        return
    }
}

Definition​

An Error is any type that implements the simple built-in error interface:

type error interface {
    Error() string
}
i, err := strconv.Atoi("42b")
if err != nil {
    fmt.Prinln("couldn't convert:", err)
    return
}

Build own error interface​

type userError struct {
    name string
}

func (e userError) Error() string {
    return fmt.Sprintf("%v has a problem with their account", e.name)
}

func sendSMS(msg, userName string) error {
    if !canSendToUser(userName) {
        return userError{name: userName}
    }
}

The built-in Errors packages​

import "errors"

var err error = errors.New("something went wrong")