Variadic arguments in options don't work

[flotwig]

Not sure if this is intended or not... but I'm seeing some unexpected behavior when trying to use variadic arguments as an option.

Here's some demo code:

const commander = require('commander')

const program = new commander.Command()

program
.command('run')
.usage('[options]')
.description('Runs some stuff')
.option('-d, --dev', 'Dev mode')
/** bunch more options here */
.option('-s, --spec <specs...>', 'Specs to run')
.action((opts) => {
  console.log(opts)
})

program.parse(process.argv)

If I run node index.js run --spec a, it works as expected and opts is a Command object with spec === "a".

However, if I try to use the optional var args like node index.js run --spec a b c, opts is a string with value b. It seems to take the value of whatever that middle argument is.

Is there a better way to do what I'm trying to do, or is this a bug? Or both? 😄

I want to avoid putting the varargs in .usage if possible, since this argument is optional and I don't want to confuse users.

Commander 2.19.0

[shadowspawn]

You can have variadic arguments, but not variadic options. You can have a repeatable option with multiple values specified but you do need to add a routine to do the collecting. See <file...> and --collect [value] under coercion in the README.

So for your option would be called like:

run --spec a --spec b --spec c

[flotwig]

Ah, thanks for clearing that up. I was trying to get globbing to work intuitively for users, so if they pass --spec * and the shell expands it to --spec a b c, it'll still work. I came up with a workaround that parses the extra arguments from Commander:

Sample code:

const commander = require('commander')

const parseVariableOpts = (fnArgs, args) => {
  const opts = fnArgs.pop()

  opts.spec = [opts.spec]

  if (fnArgs.length && opts.spec) {
    // this will parse space-delimited specs after --spec spec1 but before the next option

    const argIndex = args.findIndex(arg => arg === '--spec') + 2
    const nextOptOffset = args.slice(argIndex).findIndex(arg => arg.slice(0, 2) === '--')
    const endIndex = nextOptOffset !== -1 ? argIndex + nextOptOffset : args.length

    const extraSpecs = args.slice(argIndex, endIndex).filter(maybeSpec => {
      return fnArgs.find(fnArg => {
        return maybeSpec === fnArg
      })
    })

    opts.spec = opts.spec.concat(extraSpecs)
  }

  return opts
}

const program = new commander.Command()

program
.command('run')
.usage('[options]')
.description('Runs some stuff')
.option('-d, --dev', 'Dev mode')
/** bunch more options here */
.option('--spec <specs>', 'Specs to run')
.action((...fnArgs) => {
  opts = parseVariableOpts(fnArgs, process.argv)
  console.log(opts.spec)
})

program.parse(process.argv)

Example output:

➜  node index.js run --spec a c
[ 'a', 'c' ]
➜  node index.js run --spec a
[ 'a' ]
➜  node index.js run --spec a b c d e f g
[ 'a', 'b', 'c', 'd', 'e', 'f', 'g' ]
➜  node index.js run --spec a b c d e f g --dev
[ 'a', 'b', 'c', 'd', 'e', 'f', 'g' ]
➜  node index.js run --spec a b c d e f --dev g
[ 'a', 'b', 'c', 'd', 'e', 'f' ]
➜  node index.js run --dev --spec a b c d e f
[ 'a', 'b', 'c', 'd', 'e', 'f' ]

[shadowspawn]

There is also discussion of variadic options in #571

[shadowspawn]

Closing in favour of #571