Exclusive or relationship

[jjzieve]

With the release of 2.8.0. I see that #575
changed it so you can't use Groups and SetNames together. Is there a reason that was removed?

Using both together achieved an XOR relationship that was useful. If say, I want at least one option in a group to be required but you can't use the other options in that group at the same time.

[moh-hassan]

Can you provide example of use case

[jjzieve]

The Group example (https://github.com/commandlineparser/commandline/wiki/Option-Groups) could be one. Just imagine a world where I want to validate that the user can only --append a prefix or a suffix but not both.

[moh-hassan]

I mean case where both group and exclusive or for the same option. Both are not applicable for the same option.

[jjzieve]

Group achieves the "Required" part whereas I don't see how to use "SetName" (i.e. Mutually Exclusive Options") to say "hey at least one of these sets are required". If there's a way to achieve this XOR relationship without using both Group and SetName together I can do that but I don't know of a way (other than implementing it myself)? I don't fully understand why Group and SetName shouldn't be used together?

[moh-hassan]

Just show me example to show how both can be applied without contradiction.

[moh-hassan]

Cc @hadzhiyski
Can you help in this feature?

[moh-hassan]

If the options of group are contained in different setname, it will raise error.
If group is contained in the same setname, it has no meaning.

[jjzieve]

If the options of group are contained in different setname, it will raise error.

It did not raise an error prior to 2.8, that's why I opened this issue.

If group is contained in the same setname, it has no meaning.

It would be different setnames to achieve the XOR functionality.

So for the append example it would look like this:

class AppendToFileNameOptions
{
    //define commands in set(group) named fetch
  [Option(SetName = "prefix", Group = "append", HelpText="Prefix to append to file name")]
  public string Prefix { get; set; }

  [Option(SetName = "suffix", Group  = "append", HelpText="Suffix to append to file name")]
  public string Suffix { get; set; }

  [Option("source", HelpText="The path of a file to rename")]
  public string FilePath { get; set; }
}

And you could do:
app --prefix foo --source bar
or
app --suffix foo --source bar

But not:
app --source bar
You get this error:

ERROR(S):
  At least one option from group 'append' (prefix, suffix) is required.

or
app --suffix foo --prefix foo --source bar
You get this error:

ERROR(S):
Option: 'prefix' is not compatible with: 'suffix'.
Option: 'suffix' is not compatible with: 'prefix'.

Does that make sense?

[moh-hassan]

You can remove group and set the option Required in both sets and apply the same logic.
Let me know if this solution is reasonable.
In wiki page it is stated that both group and exclusive option are not allowed.
The change in 2.8 is taking default value into account for group.
The logic behind this constraint is:
In group, at least one option is required.
In Exclsive sets only one set is allowed.

[jjzieve]

Oh you're right, it seems setting Required = true without the group works to achieve XOR. I thought it didn't before but must've been my mistake. Thank you!

[moh-hassan]

Glad that you resolved your issue. 👍