Simplify cli.NewExitError

[gravis]

Hi,

I need to update a CLI tool because we have some deprecation warnings in the output.
While I thought I could simple return errors from commands, I end up with things like:

 f, err := os.Create("config.yml")
 if err != nil {
     return cli.NewExitError(err.Error(), 1)
 }
 defer f.Close()
 err:= project.Configure(project.Slug, os.Stdin, f)
 if err != nil {
     return cli.NewExitError(err.Error(), 1)
 }
 [...]
 return nil

It would be so much easier to simply return err in case of error, and cli would display the error, and exit with code 1. Sounds like a very reasonable default, doesn't it?

[gravis]

ie, I would like to write:

 f, err := os.Create("config.yml")
 if err != nil {
     return err
 }
 defer f.Close()
 err:= project.Configure(project.Slug, os.Stdin, f)
 if err != nil {
     return err
 }
 [...]
 return nil

instead.
It would be the icing on the cake if we could define an Exiter func to change the behaviour when an action returns a non-nil error (like using red text).

[jszwedko]

Hi @gravis,

You can achieve this behavior yourself by doing something like:

// define and instantiate a `cli.App`

err := app.Run(os.Args)
if err != nil {
  fmt.Println(err)
  os.Exit(1)
}

I can see the argument that you are making though -- I think it makes sense, but would want to think through the drawbacks. Do you have thoughts about this @meatballhat (as the original implementer of this behavior 😄)?

(It would basically just mean adding a default behavior to

cli/errors.go

Lines 74 to 91 in 1d47add

	func HandleExitCoder(err error) {
	if err == nil {
	return
	}
	if exitErr, ok := err.(ExitCoder); ok {
	if err.Error() != "" {
	fmt.Fprintln(ErrWriter, err)
	}
	OsExiter(exitErr.ExitCode())
	return
	}
	if multiErr, ok := err.(MultiError); ok {
	for _, merr := range multiErr.Errors {
	HandleExitCoder(merr)
	}
	}

)

[gravis]

Exactly was I was looking for. I wasn't obvious to me that the error was forwarded to Run. It probably needs a small example somewhere in the doc?
Thanks :)

[jszwedko]

@gravis behavior was updated in #496 to match what you described (after discovering that that was the original intent). Thanks for the report!

[gravis]

Awesome!
Thanks :)