[bug #68227] multiple inheritance no longer allowed for handle classes

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URL:
  <https://savannah.gnu.org/bugs/?68227>

                 Summary: multiple inheritance no longer allowed for handle
classes
                   Group: GNU Octave
               Submitter: rdzman
               Submitted: Fri 10 Apr 2026 09:41:36 PM UTC
                Category: Interpreter
                Severity: 3 - Normal
                Priority: 5 - Normal
              Item Group: Unexpected Error or Warning
                  Status: None
             Assigned to: None
         Originator Name:
        Originator Email:
             Open/Closed: Open
         Discussion Lock: Unlocked
                 Release: 11.1.0
        Operating System: Any
           Fixed Release: None
         Planned Release: None


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Follow-up Comments:


-------------------------------------------------------
Date: Fri 10 Apr 2026 09:41:36 PM UTC By: Ray Zimmerman <rdzman>
A common pattern in my code is to use multiple inheritance with handle
classes. This requires that each parent inherit from *handle* (to avoid the
"cannot mix handle and non-HandleCompatible classes" error), like this:


classdef ffoo < bbar & bbaz
end

classdef bbar < handle
end

classdef bbaz < handle
end


Beginning with Octave 11.1.0, when the object is cleared or goes out of scope,
this results in a warning:


octave:1> f = ffoo(); clear f
warning: error caught while executing handle class delete method:
method delete: conflicting definitions in classes 'bbar' and 'bbaz'


I believe this is related to fixing [https://savannah.gnu.org/bugs/?50011 bug
50011].

MATLAB gives no warning for this case. In Octave, however, there seems to be
no way to turn off the warning, except to turn off *all* warnings.

Because of the incompatibility with MATLAB, I believe this is a bug.

From what I can tell, it seems the only workaround at the moment is to define
a delete() method in each such child class that overrides, then explicitly
calls, *handle*'s delete() method.


classdef ffoo < bbar & bbaz
    methods
        function delete(obj)
            delete@handle(obj);
        end
    end
end









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