TheMartes / go-error-handling

Notes for my talk.

Error Handling in GO

These are just my notes to Error Handling in Go. For the full context I would suggest to checkout Go Guild Meetup Video which will tell you how to process code and following notes.

01 The Official Way

f, err := os.Open("filename.ext")
if err != nil {
    log.Fatal(err)
}

Or throw new err directly errors.New("msg") / fmt.Errorf("something")

02 Predefined Errors

type ResultError struct {}

func (e *ResultError) Error() string {
	return "Wrong Result"
}

Then Invoke it like so &ResultError{}

03 Custom Errors

type CustomError struct {
  data string
}

func (e *CustomError) Error() string {
  return fmt.Sprintf("Error occured due to... %s", e.data)
}

Then log the custom err log.Fatal(&CustomError{"nothing"})

04 - Simplifying Error Handling

Error handling can be quite repetitive

Problem: http package doesn't understand function that returns err

So we will implement new type which returns errror like this: type appHandler func(http.ResponseWriter, *http.Request) error

we will extend ServerHTTP interface with reciever of type appHandler

func (fn appHandler) ServeHTTP(w http.ResponseWriter, r *http.Request) {
	if err := fn(w, r); err != nil {
		http.Error(w, err.Error(), 500)
	}
}

• everytime ServeHTTP fails inside appHandler it will do the following error handling
• then rewrite http.HandleFunc() to http.Handle() and wrap errorGiver to appHandler

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Presentation can be found here: Google Slides

Youtube Video: TBA