Re: Help-octave Digest, Vol 99, Issue 47

[Damian]

Hi Carne,

Thanks for the explanation.

Originally I was using ParamValue, but since it failed to parse the
parameters when I added the "KeepUnmatched" option I resorted to the
optional parameters.

I have to check in my code if I run into problems using version 3.8.1
(Ubuntu package).

Best,
Damian.





On Sat, Jun 21, 2014 at 3:59 AM, Carnë Draug <address@hidden> wrote:
> On 17 June 2014 09:04, Damian <address@hidden> wrote:
>> Hello,
>>
>> Recently I run into some unexpected (for me) behavior when using
>> inputParser. Here is the example:
>>
>>     p = inputParser;
>>     p.FunctionName = 'my_function;
>>     p.CaseSensitive = true;
>>     p.KeepUnmatched = true;
>>
>>     p = p.addOptional('local', 0, @isnumeric);
>>
>>     test = {'local', 15};
>>
>>     res = p.parse(test{:})
>>
>> After executing this code, the parameter 'local' appears as unmatched,
>> even though is passed as parameter.
>>
>> If I change the KeepUnmatched attribute to 'false' I get an error
>> saying that an unmatched parameter was found (namely 'local').
>>
>> I would expect the 'local' parameter specified in 'test' to be parsed
>> without a problem. Am I missing something?
>>
>> I'm using Octave version 3.6.4.
>>
>> Thanks in advance,
>> Damian.
>
> I think you are misunderstanding what Optional means and what you
> should be using is ParamValue. Consider imread:
>
> imread ("thisfile.tif", "tiff", "index", 1:10)
>
> the first argument is required, second argument is optional, and the
> third and fourth are key and respective value. It's the same as:
>
> imread ("thisfile.tif", "index", 1:10)
>
> In your example, you are setting an optional argument named "local"
> that defaults to 0. The name for an "optional" argument is only used
> so you can access the elements from the parsed object. This means that
> with your set up, if you use
>
> foo ("local", 15)
>
> inputParser will check if the first argument passes the check for the
> optional argument. It fails, because the test is @isnumeric, but the
> value is the string "local" (so inputParser is correct to fail). If
> you set it to KeepUnmatched, then it decides that it an undeclared
> param/value pair of "local" with a value of 15 (still correct).
>
> Basically, you said it yourself "After executing this code, the
> parameter 'local' appears as unmatched, even though is passed as
> parameter.". Yes, it is passed as parameter, but you did not set
> inpurParser to look for a parameter name that has a matching value
> (ParamValue). You set it to look for an optional value. The usage of
> an Optional in inputParser is diminished in Octave because you can
> already set the defaults as in:
>
> function foo (val = 15)
>   ...
> endfunction
>
> Carne