Array arguments

[liscio]

I've been using Console for building some internal tools, and it's been going great so far. Thanks for separating it from vapor, and for the recent ConsoleKit changes!

Anyway, I was wondering today whether you folks considered allowing for an argument to be specified multiple times? For instance, say I have an input argument that can be specified multiple times. It'd be used like so:

my-command --input /path/to/input --input /path/to/other/input --output /path/to/output

Ideally, this would allow me to get an array of paths for the key "input" from a CommandContext.

Thoughts?

[calebkleveter]

I like this. I'm wondering if maybe using a comma separated list might be better though?

my-command --input /path/to/input,/path/to/other/input --output /path/to/output

[liscio]

Is there a precedent for that usage? I can't think of one myself—especially one that plays nicely when used in bash scripts, etc.

For instance, xcodebuild uses the pattern I proposed to specify multiple localization languages (-exportLanguage), find allows you to specify many duplicated switches on the command line (like -or predicates), and it's also common to think of input files in this way. Think, cat fileA fileB fileC > bigFile, for instance.

[calebkleveter]

I think it may be more common in the Python world? I haven't looked a whole lot. I'm fine going either way.

[KyleLeneau]

Just to chime in, Python's Click library does it the way @liscio mentioned but they also have an optional guard in the form of nargs: https://click.palletsprojects.com/en/7.x/options/#multi-value-options

[tanner0101]

This seems like a worthwhile addition. I think we'd need a new property wrapper for it. Something like:

@Array(name: "input")
var inputs: [String]

@Array name should be bike-shedded as there's probably something better. Maybe @Options (with an s)?

[calebkleveter]

You could also conform Array to LosslessStringConvertible.

[gwynne]

This is essentially superseded by #180