Error handling methods and related practices in Golang

In Golang, the exception system found in almost every language has been completely removed and replaced by a more concise and flexible error handling method. This article aims to introduce error handling methods and related practices in Golang.

1. Error type

In Golang, error type is the basic unit of error handling. The error type is a built-in interface type, defined as follows:

type error interface {
    Error() string
}

This interface only contains one method Error(), and the return type is a string. Therefore, any type that implements this interface can be used as an error type.

The Golang standard library contains a errors package that can be used to quickly create simple errors:

import "errors"

func main() {
    err := errors.New("some error occurred")
    fmt.Println(err)
}

Of course, we can also customize error types:

type MyError struct {
    message string
}

func (e *MyError) Error() string {
    return fmt.Sprintf("MyError: %v", e.message)
}

2. Error handling practice

In Golang, the conventional error handling includes two methods: returning error and panic. Therefore, when an error occurs, we usually have the following two ways of handling it:

2.1 Return error

Normally, we will use the error as the return value of the function for the caller to handle. For example:

func divide(a, b int) (int, error) {
    if b == 0 {
        return 0, errors.New("division by zero")
    }
    return a / b, nil
}

func main() {
    result, err := divide(6, 2)
    if err != nil {
        log.Fatal(err)
    }
    fmt.Println(result)
}

This function returns the error as the second return value. When calling this function, we usually first determine whether the error is empty, and if not, perform corresponding error handling.

2.2 Panic

In some cases, when the program has an unrecoverable error, we can use the panic keyword to throw a program exception. At this point, the program will stop execution and print out the corresponding error message.

func checkName(name string) {
    if name == "" {
        panic("name can not be empty")
    }
}

func main() {
    name := ""
    checkName(name)
    // other actions
}

In the above code, when name is empty, the program will throw an exception and stop execution.

3. Error handling best practices

In order to ensure the readability and maintainability of the code, we need to follow some error handling best practices.

3.1 Avoid abusing Panic

In Golang, Panic is only used to handle unrecoverable errors. Therefore, when writing code, whether you throw panic yourself or catch panic, you should treat it carefully. Try to limit the use of panic to uncontrollable abnormal situations.

3.2 Return error code

In some cases, errors can be represented by returning error codes. For example, the error codes in HTTP requests are 404 Not Found, 500 Internal Server Error, etc. Returning error codes can effectively convey error information, but you also need to pay attention to the design of error codes. Error codes should have unique, identifiable, readable and other attributes.

3.3 Return error description

When an error occurs in a function, returning a detailed error description can help the user quickly locate the error location and cause. You can also customize error types to achieve more specific error descriptions.

type MyError struct {
    message  string
    location string
}

func (e *MyError) Error() string {
    return fmt.Sprintf("Error occurred in %s: %s", e.location, e.message)
}

4. Conclusion

In Golang, exceptions are completely removed, and error handling is given a more flexible and concise practice. Correct handling and delivery of error information can ensure the stability and maintainability of the program. Following the above error handling best practices can help us write more robust, reliable, and readable code.

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