bugGNU Octave - Bugs: bug #61676, Assigning classdef objects to...


bug #61676: Assigning classdef objects to other types does not call converter methods

Submitter:  Nicholas Jankowski <nrjank>
Submitted:  Wed 15 Dec 2021 03:37:49 AM UTC
Category:  Classdef Severity:  2 - Minor
Priority:  5 - Normal Item Group:  Incorrect Result
Status:  None Assigned to:  None
Originator Name:  Nicholas Jankowski Open/Closed:  * Open
Release:  * dev Operating System:  * Any
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Wed 15 Dec 2021 03:37:49 AM UTC, original submission:  

as initially discussed at

A = [1:5];
B = myclass
A(4) = B

according to expected matlab behavior, Octave should first look to myclass for a method the same name as the class of A, absent that it should pass B to A's constructor to see if it can handle a myclass object, otherwise it should error.

Trying a test class:

classdef myclass
    ## no properties

  methods (Access = public)
    function this = myclass (varargin)
      if (nargin != 0 )
        error ("Invalid call");

  methods (Access = public)
    function retval = double (this)
      retval = NaN;

this should work as a converter to replace A(4) with NaN, however I instead get:

however I instead get:

>> A(4)=B
error: operator =: no conversion for assignment of 'object' to indexed 'matrix'

the only similar bug I see is an old closed bug #32651. it seems that was before classdef, but described a similar sounding issue with method precedence, where Octave "follows Mathwork's published function precedence whereas Matlab does not" preventing Octave from ever calling converter functions.

Maybe the fix here can borrow from what was learned there?

Nicholas Jankowski <nrjank>
Project Member


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    Follow 3 latest changes.

    Date Changed by Updated Field Previous Value => Replaced by
    2022-05-16 nrjank CategoryOctave Function Classdef
    2021-12-16 nrjank Dependencies- patch #10102 is dependent
    2021-12-15 nrjank Summaryclassdef converter methods are not called Assigning classdef objects to other types does not call converter methods

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