errors.New()

fmt.Errorf()

var (
    ErrNotFound = errors.New("resource not found")
    ErrInvalidInput = errors.New("invalid input")
)

func GetResource(id int) (interface{}, error) {
    // ...
    if resource == nil {
        return nil, ErrNotFound // 返回預(yù)定義的錯(cuò)誤
    }
    // ...
}

errors.Is()

errors.As()

type MyError struct {
    Code int
    Message string
}

func (e *MyError) Error() string {
    return fmt.Sprintf("Error Code: %d, Message: %s", e.Code, e.Message)
}

func SomeFunction(input string) error {
    if input == "" {
        return &MyError{Code: 1001, Message: "Input cannot be empty"}
    }
    return nil
}

func main() {
    err := SomeFunction("")
    if err != nil {
        myErr, ok := err.(*MyError)
        if ok {
            fmt.Println("Error Code:", myErr.Code)
        }
    }
}

errors.Is()

errors.Join()

errors.Is()

errors.As()

import (
    "errors"
    "fmt"
)

func processData(data []int) error {
    var errs []error

    for _, val := range data {
        if val < 0 {
            errs = append(errs, fmt.Errorf("invalid value: %d", val))
        }
    }

    return errors.Join(errs...)
}

func main() {
    data := []int{1, -2, 3, -4, 5}
    err := processData(data)

    if err != nil {
        if errors.Is(err, errors.New("invalid value: -2")) { // 這里的errors.New僅用于比較，實(shí)際應(yīng)該預(yù)定義錯(cuò)誤
            fmt.Println("Found invalid value error")
        }
        fmt.Println("Errors:", err)
    }
}

errors.Is

panic

panic

defer

recover

panic

func SafeFunction() {
    defer func() {
        if r := recover(); r != nil {
            fmt.Println("Recovered from panic:", r)
            // 可以進(jìn)行日志記錄、清理資源等操作
        }
    }()

    // 可能會(huì)發(fā)生panic的代碼
    panic("Something went wrong!")
}

func main() {
    SafeFunction()
    fmt.Println("Program continues after panic.")
}

defer

recover

panic

defer

recover