How to embed exit code in error to use when terminating program?

Question

How can I embed an exit code in a go error, bubble it up, and then exit with the exit code when I handle the error?

For example:

func main () {
  foo, err := foo()
  if err != nil{
    fmt.Printf("error thrown, exit code: %v", err )
  }
  // I can parse the exit code out of err, but that seems wrong... 
  // how can I exit with the exit code cleanly? do i need to create a custom error that I bubble up and handle?
  os.Exit(1)
}

func foo() (string, err) {
  bar, err := bar()
  if err != nil {
     return "", fmt.Errorf("foo fails b/c bar fails %v": err)
  }
}

func bar() (string, err) {
  exitCode := 208
  return "", fmt.Errorf("some error happened in bar, exit code: %v", exitCode)
}

Brits · Accepted Answer · 2021-03-17 23:07:59Z

You can do this by creating your own type that implements the error interface and then using error wrapping (see this blog post for more info). The result is something like:

package main

import (
    "errors"
    "fmt"
    "os"
    "strconv"
)

type fooErr int

func (e fooErr) Error() string { return strconv.Itoa(int(e)) }

func main() {
    errCode := 0
    _, err := foo()
    if err != nil {
        var e fooErr
        if errors.As(err, &e) {
            fmt.Printf("error thrown, exit code: %v", e)
            errCode = int(e)
        } else {
            fmt.Printf("error thrown, dont have a code: %v", err)
            errCode = 1 // default code...
        }
    }
    // I can parse the exit code out of err, but that seems wrong...
    // how can I exit with the exit code cleanly? do i need to create a custom error that I bubble up and handle?
    os.Exit(errCode)
}

func foo() (string, error) {
    _, err := bar()
    if err != nil {
        return "", fmt.Errorf("foo fails b/c bar fails %w", err)
    }
    return "OK", nil
}

func bar() (string, error) {
    exitCode := fooErr(208)
    return "", fmt.Errorf("some error happened in bar, exit code: %w", exitCode)
}

Try it in the playground.

Collectives™ on Stack Overflow

How to embed exit code in error to use when terminating program?

1 Answer 1

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

Comments

Your Answer

Sign up or log in

Post as a guest

Related