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From Paul King <pa...@asert.com.au>
Subject Re: Example of CliBuilder with "optionalArg: true"?
Date Tue, 09 Feb 2016 02:07:41 GMT
I think we had some improved handling for optional args in some spikes
we did for newer versions of the CLI processing stuff. But none of
that has been taken forward yet.

In the interim, you can peek at return types as per your examples
above or sneak down into the underlying implementation - just realise
that we don't make any guarantees about future breaking changes if you
do start using the underlying methods. It would look something like:


if (options.f) {
  def f = options.getOptionValue('f')
  if (f) println "found arg $f"
  else println "flag set with no optional arg"
}

And you'd have to manage calling getOptionValues where needed too.

Cheers, Paul.


On Tue, Feb 9, 2016 at 8:33 AM, David M. Karr
<davidmichaelkarr@gmail.com> wrote:
> On 02/08/2016 09:11 AM, Russel Winder wrote:
>>
>> On Tue, 2016-02-02 at 19:56 +0000, KARR, DAVID wrote:
>> […]
>>>
>>> With a  simple script like this:
>>> ----------------
>>> def cli = new CliBuilder()
>>> cli.with {
>>>    f(args: 1, optionalArg: true, "set a value")
>>> }
>>> def options = cli.parse(args)
>>> def fval = options.f
>>> println "fval[" + fval + "] class[" + fval.getClass().getName() + "]"
>>> def fvalue = options.fs
>>> println "fvalue[" + fvalue + "]"
>>> ---
>>>
>>> If I run this with "-f abc", I get:
>>> --------------
>>> fval[abc] class[java.lang.String]
>>> fvalue[[abc]]
>>> ----------------
>>>
>>> But if I run it with "-f", I get:
>>> ------------
>>> fval[true] class[java.lang.Boolean]
>>> fvalue[true]
>>> -------------
>>
>> And if you run without -f on the command line you get:
>>
>> fval[false] class[java.lang.Boolean]
>> fvalue[false]
>>
>> So I think we are looking at this being a feature of options with the
>> optionalArg property set. Without it not having an argument to -f
>> fails.
>>
>>> I suppose I could hack something with this information, but I would
>>> think there would be something more explicit to tell me whether an
>>> argument was supplied for the option.
>>
>> Thinking about this, I would say it is right that this behaviour is a
>> feature, and that it is what the code has asked for: an option that can
>> deliver presence or a value. When the is a value deliver it, otherwise
>> deliver a Boolean stating whether the flag was present.
>>
>> Clearly managing this type of option is non-trivial, but I think this
>> is not a bug.
>>
> Thanks for doing that analysis.
>
> Whether it's a bug is debatable, but I think it's clear that overloading
> behaviors often create confusion.  A friendlier interface would separate the
> notion of "presence of the option" from "value of the argument".  However,
> doing that might make all references to options more verbose, which is
> certainly not ideal.
>
> I suppose an improvement could be made by just putting a little pseudocode
> algorithm in the doc that shows how you would either retrieve a value if
> it's present, or determine it's not there, I suppose by checking the class
> of the value returned from "options.<option>".  The only time you have a
> value is when the class is "java.lang.String".  Would that be correct?

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