[bug #68108] classdef objects do not support creation of initialized arrays

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URL:
  <https://savannah.gnu.org/bugs/?68108>

                 Summary: classdef objects do not support creation of
initialized arrays
                   Group: GNU Octave
               Submitter: mag
               Submitted: Sun 01 Mar 2026 10:02:32 PM UTC
                Category: Classdef
                Severity: 3 - Normal
                Priority: 5 - Normal
              Item Group: Unexpected Error or Warning
                  Status: None
             Assigned to: None
         Originator Name: Mark Goldberg
        Originator Email:
             Open/Closed: Open
         Discussion Lock: Unlocked
                 Release: 11.1.0
        Operating System: Any
           Fixed Release: None
         Planned Release: None


    _______________________________________________________

Follow-up Comments:


-------------------------------------------------------
Date: Sun 01 Mar 2026 10:02:32 PM UTC By: Mark Goldberg <mag>
The ablity to create initialized arrays of objects is fundamental to OO design
but remains unsupported for classdef objects in GNU Octave 11.1.0. For
example, a class that operates on location data, would be reasonably expected
to form an array of location objects given an array of lat/lon
(latitude/longitude) coordinates.

Octave does support the capability with structs. One could easily define a
'Loc' struct with 'lat' and 'lon' fields and construct an initialized array of
'Loc' from an array of lat/lon data. However the same cannot be accomplished
in a classdef.

MATLAB supports the capability with both structs and classdef objects.

MRE: Given this simple value class.

classdef mre
    properties
        A
    end
    methods
        function obj = mre(a)
            if nargin > 0
                obj.A = a;
            end
        end
    end
end


The following fails with: "error: can't perform indexing operation on array of
mre objects"

m(1,3) = mre();
c = num2cell(1:3);
[m.A] = c{:};


However this works as expected:

s(1,3) = struct('A',[]);
c = num2cell(1:3);
[s.A] = c{:};


Results

octave:124> s
s =
  1x3 struct array containing the fields:
    A

octave:125> s(1)
ans =
  scalar structure containing the fields:
    A = 1

octave:126> s(2)
ans =
  scalar structure containing the fields:
    A = 2

octave:127> s(3)
ans =
  scalar structure containing the fields:
    A = 3









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