nargs=inf can't be used as last optional argument if a position argument follows

[António Miguel de Jesus Domingues]

I spotted this issue when using an optional argument with infinite number of args, and a positional argument. When the last optional arg has nargs=Inf it will also gobble up the required args that follow.

Test code:

Example that works as intended:

Rscript argparser_test.R --inf a b c --one 2 something
[1] "This is a test script"
[[1]]
[1] FALSE

$help
[1] FALSE

$opts
[1] NA

$inf
[1] "a" "b" "c"

$one
[1] 2

$pos
[1] "something"

However when placing the inf right before mock positional argument causes an error:

Rscript argparser_test.R --one 2 --inf a b c something
usage: argparser_test.R [--] [--help] [--opts OPTS] [--inf INF] [--one
       ONE] pos

Infinite nargs is causing issues

positional arguments:
  pos         mock argument

flags:
  -h, --help  show this help message and exit

optional arguments:
  -x, --opts  RDS file containing argument values
  -i, --inf   Character argument
  -o, --one   Integer argument.

Error in parse_args(p, argv = commandArgs(TRUE)) : 
  Missing required arguments: expecting 1 values but got 0 values: ().
Execution halted

> packageVersion("argparser")
[1] ‘0.6’

Is this an intended behaviour? I would expect that it would be possible to place optional arguments anywhere before the positional arguments.

Cheers,
António

[David Shih]

This is expected behaviour. Please read ?add_argument.

If you have a fix that does not break existing features, feel free to send a pull request.

[António Miguel de Jesus Domingues]

Cheers @David Shih I should have read the docs more throughly before posting

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I don’t have a solution at the moment, and since this is not critical, we can leave it at that.