name for a mutually inclusive relationship

[Joe Pfeiffer]

Ethan Furman <ethan at stoneleaf.us> writes:

> On 2/24/21 1:54 PM, 2QdxY4RzWzUUiLuE at potatochowder.com wrote:
>> Ethan Furman wrote:
>
>>> I didn't say it was a good example.  ;-)  Hopefully it gets the idea across.
>> Ditto.  ;-)
>> IMO, the whole idea of "my program has two options, and the user has
>> to
>> specify both or neither," isn't a question of whether or not the
>> argument parsing library supports it, but a question of whether or not
>> it's a good API.
>
> Like I said, at this moment I don't have a good example, only an awareness that such a thing could exist and I don't know the name for it (if it has one).
>
> So far I have seen that there are even fewer good use-cases than I might have guessed, and that no one seems to have a name for the general idea.

Do you have a specific problem you're trying to solve?  That might help
us understand the question better.