feat: support mix of required and conflicting options

[sagargurtu]

Current Behavior

program
  .addOption(new Option('-p, --port <number>', 'port number').makeOptionMandatory())
  .addOption(new Option('--disable-server', 'disables the server').conflicts('port'))

In the above example, if both --port and --disable-server are provided, it shows conflicting error as expected. However, if only --disable-server is provided, it throws an error that says --port was not specified.

program
  .addOption(new Option('-p, --port <number>', 'port number'))
  .addOption(new Option('--disable-server', 'disables the server').conflicts('port'))

If --port is not marked as mandatory, the program runs if neither option is provided.

Desired Behavior

A way to specify either of two conflicting options as mandatory. In the above example, --port should be mandatory only if --disable-server is not provided.

• If both --port and --disable-server are provided, it should show conflicting error as expected.
• If only --disable-server is provided, it should not throw any error.
• If only --port is provided, it should not throw any error.
• If neither option is provided, it should throw an error that says --port was not specified.

[shadowspawn]

I researched some constraints offered by other libraries a while ago: #1802 (comment)

I think prior art for what you describe are:

• Oclif has exactlyOne
• Python argparse has add_mutually_exclusive_group(required=True)

(In general I am not planning to add more constraints, unless there is sufficient interest.)

[shadowspawn]

This issue has not had much activity in six months. It isn't likely to get acted on due to this report.

Thanks for the suggestion. It is quite a lot of work robustly supporting option interactions in Commander. There are lots of possible constraints, and not many requests. Not planning to add more without clarity that it is solving a problem that enough people would benefit from.

Feel free to open a new issue if it comes up again, with new information and renewed interest.

Thank you for your contributions.