Error Handling

I am continuing to learn more about Go and its history.

The language follows idioms.

Idioms of Go

• get the job done
• one way of doing things
• be explicit
• build things by composing them

Fundamentals of Software Development

One of the most important aspects of my job is writing meaningful error messages. It’s something a lot of people don’t ever stop to consider: where do error messages come from?

Software developers create tools used by others and by nature of the broad interconnected tooling systems in computers and the internet at-large it cannot be difficult to imagine how collaboration is vitally important. Error messaging is how a software developer communicates with their users about expected and unexpected behavior. I believe that software which does not provide meaningful error messages (here’s what went wrong, here’s how to fix it) is not well-written software.

Error handling is a fundamental skill for software engineering.

Error Handling in Go

Review the following go packages for an example of returning an error. Source from golang.org

greetings.go

package greetings

import (
    "errors"
    "fmt"
)

// Hello returns a greeting for the named person.
func Hello(name string) (string, error) {
    // If no name was given, return an error with a message.
    if name == "" {
        return "", errors.New("empty name")
    }

    // If a name was received, return a value that embeds the name
    // in a greeting message.
    message := fmt.Sprintf("Hi, %v. Welcome!", name)
    return message, nil
}

main.go

package main

import (
    "fmt"
    "log"

    "example.com/greetings"
)

func main() {
    // Set properties of the predefined Logger, including
    // the log entry prefix and a flag to disable printing
    // the time, source file, and line number.
    log.SetPrefix("greetings: ")
    log.SetFlags(0)

    // Request a greeting message.
    message, err := greetings.Hello("")
    // If an error was returned, print it to the console and
    // exit the program.
    if err != nil {
        log.Fatal(err)
    }

    // If no error was returned, print the returned message
    // to the console.
    fmt.Println(message)
}

Notes

• the log and errors packages are golang builtins
• I would want to use constants for error messages, e.g., errors.New(UNEXPECTED_ERROR) or errors.New(EXTERNAL_SERVICE_ERROR) however Go does not support this pattern since it alternates between camelCase and PascalCase to denote variables which are global to a file vs. global to a package (respectively)

Willow