Xor is ignored with positional arguments

[mitar]

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I would like to do something like:

run --defaults

or:

run foo bar

but prevent:

run --defaults foo bar

It seems xor for positional arguments (flag with arg:"") does not do anything: there is no error if both are provided.

[alecthomas]

That's correct, xor is currently only applicable to flags. Seems reasonable though.

[everdrone]

I'm trying to add a --version flag, with that flag no positional arguments are required what would be the correct way of doing that if xor ignores positionals?

[mitar]

Use VersionFlag.

[WillAbides]

I have a need for this as well.

@alecthomas, you said "Seems reasonable though", but that was a while ago. Before I start diving into this, are you still open to a PR for to include positional arguments in xor?