@ArgGroup with @Option methods fail with NullPointerException

[a2geek]

What I'm trying to do: I have an existing API that has multiple values for list formats and I would like to switch them on with a flag type mechanism. They are mutually exclusive -- you can't have a short and a long list format, for instance.

This seems to be a great chance to use @ArgGroup(exclusive = true) and @Option(...) on a method in the exclusive options. The method simply sets the correct value to the actual parameter. (There are multiple methods settings values. One for each list format.)

What happens: A NullPointerException is generated like this:

$ bin/picocli-experiments list file1 file2
NullPointerException: null while processing argument at or before arg[0] 'list' in [list, file1, file2]: java.lang.NullPointerException

If I switch from a method to a boolean flag annotated with @Option, and then write the if-logic to calculate the value, it works fine. But that's pretty ugly.

From what little I've been able to determine from debugging, the scope is never set in Interpreter.applyGroupDefaults() in line 11075 -- the if (arg.scope().get() != null) is what fails.

Using picocli version 4.0.4.

(P.S. Excellent tool, really like it a lot.)

(P.P.S. sample.zip is attached for a more cohesive use case.)

[remkop]

Thanks for raising this.
Looking at it...

[remkop]

I’ve only been able to spend a little bit of time investigating, but I suspect that this only happens in subcommands. All my tests for argument groups are with top-level commands. Definitely some problem in the initialization.
Still need to look further...

[a2geek]

Thanks for the quick confirmation! I was uncertain if I was missing something or not. I'll go with the alternative mechanism for now then. :-)

[remkop]

Fixed in master. Thanks again for raising this!