Golang is a strongly typed programming language that provides a good error handling mechanism at the language level. Error handling is an essential part of the Golang development process. Its design concept is to separate error handling from the code and business logic to achieve more readable and maintainable code.
In Golang, the basis of the error mechanism is a built-in type - error
. error
is an interface type in Golang. It defines a method: Error()
, which is used to return error information. error
The expected exception can be passed to the caller as the return value of the function, or as a parameter to the call of other functions.
When an error occurs in a function, it will return a non-nil error
object that contains error information. The caller can determine whether the function has been executed successfully by checking the returned error. If nil is returned, it means that the function execution was successful; otherwise, it means that the function execution failed.
Below, we will introduce some common error handling mechanisms and techniques in Golang:
defer
mechanism to delay The execution of a function is not executed until the function returns. defer
Commonly used for operations such as releasing resources, closing files, clearing buffers, etc. recover
is used to restore the program control flow after [panic
](https://tour.golang.org/basics/13) so that the program can continue to execute normally. It can only be called in defer
, otherwise it will not work.
In Golang, you can use the defer
and recover
mechanisms to implement error handling, that is, use recover# in the
defer statement ##To capture the error information generated during function execution, then determine the error type and handle it accordingly.
func processFile(filename string) error { file, err := os.Open(filename) if err != nil { return err } defer file.Close() // Read the file here... return nil } func main() { err := processFile("/path/to/myfile.txt") if err != nil { // Handle the error here... fmt.Println(err) } }
defer; and finally
nil Return, indicating that the function was executed successfully. In the main function, if the calling function returns a non-nil error, it means that the function execution failed, so we need to perform corresponding error handling operations.
Error() method. Custom error types can make the code more readable and reduce the possibility of errors; at the same time, it can also improve code reusability.
type customError struct { message string code int } func (e *customError) Error() string { return fmt.Sprintf("%s [%d]", e.message, e.code) } func processFile(filename string) error { file, err := os.Open(filename) if err != nil { return &customError{"Error opening file", 1001} } defer file.Close() // Read the file here... return nil } func main() { err := processFile("/path/to/myfile.txt") if err != nil { // Handle the error here... fmt.Println(err) } }
customError, which contains the error message and error code. In the
processFile() function, if the file cannot be opened, a
customError object is returned. In the main function, if an error occurs, call the
Error() method to obtain the error information.
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