Go language - custom error

Catalog

Preface

Built in package creation error object

Customize error Interface implementation

---

Preface

error yes go A data type in a language , Built in interface . Defines a method Error() string

error Interface

error Interface implementation --errorString Structure , Realization Error Method .

Built in package creation error object

go Language built in errors Under bag New() Functions and fmt Under bag Errorf(), You can create one of them error object .

func main() {
	err1 := errors.New(" adopt errors.New() Error creating ")
	fmt.Printf("err1:%v,  type :%T\n", err1, err1)

	err2 := fmt.Errorf(" adopt fmt.Errorf() Error creating ")
	fmt.Printf("err2:%v,  type :%T\n", err2, err2)
}

Customize error Interface implementation

It can be seen from the previous words ,error The interface is very simple . To achieve error Interface , Just customize a structure , Realization Error() The method can .

Let's customize the implementation errror Interface . Function input the value of age to judge , An error is reported when the size is too large or too small .

type AgeError struct {
	msg string
	age int
}

func (a *AgeError) Error() string {
	return a.msg + ",  Age is :" + strconv.Itoa(a.age)
}

func main() {
	age, err := ageVerification(200)
	if err != nil {
		fmt.Println(err)
	} else {
		fmt.Println(age)
	}
}

func ageVerification(age int) (int, error) {
	if age > 150 || age < 0 {
		return age, &AgeError{" Age is illegal ", age}
	}
	return age, nil
}