cli: Flag errors are not `ExitCoder`

my urfave/cli version is

v2.2.0

Checklist

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Dependency Management

My project is using go modules.
My project is using vendoring.
My project is automatically downloading the latest version.
I am unsure of what my dependency management setup is.

Describe the bug

If you mark a flag as “required” for instance and it is missing, then the error that is bubbled up to the root cli.App.Run(..) call does not satisfy the required interfaces for HandleExitCoder.

To reproduce

Have a required flag
Have a panic after the call to HandleExitCoder
Call the CLI without it

Observed behavior

The panic is called

Expected behavior

HandleExitCoder calls os.Exit(..)

Additional context

It should be possible to define the exit code for a specific flag (or for the application in general) if there are flag errors. Be them required, or not defined as a flag.

About this issue

Original URL
State: open
Created 4 years ago
Reactions: 2
Comments: 15 (5 by maintainers)

Most upvoted comments

Though, now that I have looked more deeply at the code, there is a slight problem with having the flags define their own exit codes. What happens if multiple flags produce errors (currently only required).

Should the first win?
Should the last win?
Should the highest value win?
Should the lowest non-zero win? (What about negative values?)

I have looked at some what other programs do (such as posix exit). It seems to be undefined if you try and use a negative number, or if you try and use a number outside of [0, 255] since that is all that wait_pid will return. All this is to say that the last option (lowest wins) should probably be never considered.

Nokel81 on Mar 24, 2020

I think returning an ExitCoder should be part of it.

Another option (I like this one because it is the most customization while still having a fast path for global setting):

Have a hierarchy of exit codes: use app setting or, if set, command setting or, if set, flag setting

Nokel81 on Mar 24, 2020

Yes but what should that exit code be? Should it be static and unchanging? I think that it should be able to be set by users of this library.

Nokel81 on Mar 23, 2020