Propagation and handling of errors in Golang functions

In Go functions, functions can propagate errors by returning error objects, and the calling function is responsible for processing. Error handling methods include: ignoring errors, logging, warning and returning errors. In practice, you can use error handlers to easily handle errors that may occur, and use descriptive error messages to help identify and handle errors. Additionally, the errors.Is and errors.As functions can be used for comparison and type conversion errors.

Propagation and handling of function errors in Go

In the Go language, a function can return an error Object that can give you detailed information about why function execution failed. Error handling is an important Go language concept that helps you write robust and maintainable code.

Error propagation

When a function returns an error object, it is propagating errors. This means that the function that called it is now responsible for handling the error. The function can return the error itself, or handle it through other means such as logging or alerting.

Let's look at an example:

func divide(a, b int) (int, error) {
  if b == 0 {
    return 0, fmt.Errorf("除数不能为 0")
  }
  return a / b, nil
}

The divide function returns an error when the divider is 0. The function that called the divide function is now responsible for handling this error:

func main() {
  result, err := divide(10, 2)
  if err != nil {
    fmt.Println("除法出错：", err)
  } else {
    fmt.Println("结果：", result)
  }
}

Error handling

Error handling is a way of handling errors. An error handler is a function that receives an error object and handles it. It can be implemented in different ways, for example:

• Ignore errors: Only handle the return value of the function, ignoring potential errors.
• Logging errors: Write errors to the log file using methods such as log.Printf or fmt.Println.
• Alert errors: Send alerts about errors to operations staff via email, text message, or other mechanism.
• Return Error: Propagate the error to the calling function.

Practical case

Suppose you have the following function:

func getFromDB(id int) (string, error) {
  // 从数据库中获取数据
  // ...
  return data, nil // 模拟成功的情况
}

You can use an error handler to easily handle what may happen in the getFromDB function Error:

func main() {
  data, err := getFromDB(1)
  if err != nil {
    // 处理错误，例如：
    // - 忽略错误
    // - 日志记录错误
    // - 告警错误
    return
  }
  // 使用数据...
}

Other Tips

• Always check the error object returned by a function, even if you are not sure whether it will return an error.
• Use descriptive error messages so errors can be easily identified and handled.
• Consider using the errors.Is and errors.As functions for comparison and type conversion errors.

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