bugGNU Octave - Bugs: bug #62418, inputParser fails because of...


bug #62418: inputParser fails because of function not returning argument

Submitter:  Georg Wiora <gwiora>
Submitted:  Thu 05 May 2022 02:23:05 PM UTC
Category:  Interpreter Severity:  3 - Normal
Priority:  5 - Normal Item Group:  Regression
Status:  Wont Fix Assigned to:  None
Originator Name:  gwiora Open/Closed:  * Closed
Release:  * 7.1.0 Operating System:  * Microsoft Windows
Fixed Release:  None Planned Release:  None
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Fri 06 May 2022 06:37:00 AM UTC, comment #2: 

Thank you for the hint to news file. This means that the interpreter is OK, but inputParser class needs to be fixed. I will file a new bug report for this.

Georg Wiora <gwiora>
Thu 05 May 2022 05:49:49 PM UTC, comment #1: 

This was changed for compatibility with Matlab. It also fails there:

>> {pack()}
Error using pack
Too many output arguments.

The equivalent in Octave 7.1.0:

>> {pack()}
error: pack: function called with too many outputs
error: called from

See also this note in the NEWS file for Octave 7:

> - Calling a user-defined function with too many inputs or outputs is now
> an error.  The interpreter makes this check automatically.  If a
> function uses varargin then the check is skipped for function inputs,
> and if a function uses varargout then the check is skipped for function
> outputs.  Input validation for functions typically begins with checking
> that the number of inputs and outputs match expectations.  Existing code
> can be simplified by removing these checks which are now done by the
> interpreter.  Typically, code blocks like the following can simply be
> deleted.
>         ## Checking number of inputs
>         if (nargin > 2)
>           print_usage ();
>         endif
>         ## Checking number of outputs
>         if (nargout > 1)
>           print_usage ();
>         endif

Like described in the NEWS file, one way to adapt your code would be to define the function in the function handle `v` with `varargout`.

Overall, this is an expected change in behavior between Octave 6 (and earlier) and 7 (and later).

Closing as won't fix.

Markus M├╝tzel <mmuetzel>
Project Member
Thu 05 May 2022 02:23:05 PM UTC, original submission:  

The validate_arg function fails in octave 7.1.0 at the marked position while it worked up to 6.4

function validate_arg (this, name, val, in)
        % Check validation result to be empty in case of the use of validateattributes function
        % An empty result will be interpreted as valid arguments
-->        check = {val(in)};
        if (~isempty(check) && ~val(in))
          this.error (sprintf ("failed validation of %s with %s", toupper (name),func2str(val)));
        this.Results.(name) = in;

The reason is that val() is a function handle for validateattributes() that checks the validity of the in parameter and does only return a result if the test fails. If everything is ok it does not return a result.
This seems to be checked by the interpreter in the cell array operator: {val(in)} and the interpreter produces the follwoing error message:

error: validateattributes: function called with too many outputs
error: called from
    dirPlus>@<anonymous> at line 142 column 22
    validate_arg at line 507 column 15
    parse at line 394 column 9
    dirPlus at line 177 column 3
    SPF_OctaveJobEval at line 62 column 11
stopped in validate_arg at line 507 [C:\Software\SPF_Backend_as\deployment\octave_service_image\workspace\inputParser.m]

It seems that the interpreter insists on having an output when called inside the cell array operator. This is different from the previous behaviour.

Georg Wiora <gwiora>


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    Follow 2 latest changes.

    Date Changed by Updated Field Previous Value => Replaced by
    2022-05-05 mmuetzel StatusNone Wont Fix
        Open/ClosedOpen Closed

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