Disable "duplicates" behaviour

[stevage]

If you specify a flag multiple times it will get turned into an array containing all the values in order.

$ node examples/reflect.js -x 5 -x 8 -x 0
{ _: [], x: [ 5, 8, 0 ], '$0': 'examples/reflect.js' }

This is surprising, and undesirable behaviour to me. I'd expect the last argument to override the previous ones. Is there a way to achieve this?

[bcoe]

what if we added array parsing as one the optional configuration settings in yargs-parser?

https://github.com/yargs/yargs-parser#configuration

[stevage]

Yep, something like:

• "duplicate-arguments": "array" (current behaviour)
• "duplicate-arguments": "last" (keep the rightmost)
• "duplicate-arguments": "first" (keep the first)

Possibly an option where subsequent arguments are not interpreted as that argument. So app --foo --foo is interpreted as having a foo boolean argument, and a freetext positional argument whose value is --foo.

[bcoe]

@stevage my temptation is to start simple, with:

array: true <-- current behavior.
array: false <-- take the last argument provided.

I think this would address 99% of use-cases, without making the configuration too complicated.

[stevage]

Agree with the 99% of the use cases bit, but with boolean values you're closing the door to supporting the others later.

[bcoe]

@stevage my temptation would be to support the 99% case, and we can revisit this decision in the future.

I'll make an effort to get this additional configuration option implemented at some point this weekend (I'm hoping to have some cycles to hack on OSS).

[pluma]

@bcoe I gather you didn't get as many cycles to hack on OSS as you were anticipating. Is there any progress on this issue?

Expanding on the original issue, it would be useful to be able to specify this both a global default as well as a per-option setting. In most cases I would expect string options to be only passed once and having to specify this every time would be excessive. But for some options it makes sense to allow multiple values and array type conflicts with trailing arguments, so the "duplicates" behaviour is exactly what I would want there.

[laggingreflex]

@bcoe I'm trying to add this feature through yargs-parser, checkout this pr, but I'm not sure about where this config should be specified from. With the current PR it would require one to put {"yargs": {"duplicate-arguments-array": false}} in their package.json due to how yargs passes "configuration" to yargs-parser. Please review it and suggest a better way if possible..

[laggingreflex]

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