No built-in way to access parent command from subcommand?

[michaelpj]

A natural thing to do with parent commands is define options that will apply to all the subcommands. However, it's not terribly convenient to access the parent command from the subcommand: you have to rely on whatever creates the CommandLine to thread everything around.

Similarly, the provided IParseResultHandlers don't make it easy to pass things around.

I think what would be most convenient for me would be for a subcommand to receive an instance of its parent command as a constructor argument. That way everything is well-typed and it's easy to access the options of parent commands.

[remkop]

You raise a good point.

I’m thinking to provide an additional @ParentCommand annotation to address this.

A reference to the parent command will be injected to any fields annotated with @ParentCommand. This also provides type safety while not imposing any constraints on subcommand constructors.

Would that work for you?

[michaelpj]

Yes, that should do the job.

(Incidentally, I don't think the requirements on constructors (there must be a zero-arg constructor) for commands are documented anywhere.)

[remkop]

Ok. Thanks for pointing out the docs can be improved.

By the way, do zero-arg constructors work for you or are you also interested in using a factory like requested in #169 ?

[michaelpj]

Zero-arg constructors are fine for me at the moment, although it would be kind of neat to be able to use a factory.

[remkop]

Pushed the new @ParentCommand feature to master.
Please verify.

[remkop]

Reopening: still need to update the user manual.

[remkop]

This issue has been addressed in picocli 2.2, which is now available on JCenter and Maven Central.
See the release notes for details.