MATLAB: Changing property attributes in a value class

objects class property attributes

Is there a way to change the attributes of a class without using dynamicprops? I would like to be able to hide and reveal properties based on how objects are being used. The properties would all be defined in the class definition, but I can't find a way to change the attributes after the object is created.

Best Answer

I don't think that this "hide and reveal" approach is sound/wise. You can implement whatever logic in your methods so they work differently depending on the context, but what do you mean by "hiding methods/properties"? Could you not just avoid using them when not relevant? Very few end users really use class/object introspection mechanisms actually, and in my opinion it would be a mistake to try hiding anything to those who do. Actually, as a user, I much prefer having a clean object/class that triggers an error() when I am using one of its methods inappropriately, than a class that tricks introspection mechanisms.

I don't think that you can dynamically make private properties/methods public and vice versa. If you really want to manage hiding properties/methods, the only trick that I can think of is to overload METHODS, FIELDNAMES, and PROPERTIES. I don't think that it would be wise to overload METACLASS, because you would not be able to reproduce easily its output.

Related Solutions

MATLAB: Modifying an immutable/protected variable of a subclass in a superclass method

You're trying to break the fundamental model of OOP: encapsulation. The whole concept of protected properties is that only the class (or its subclasses) can modify them. A superclass has no way to modify the properties of its subclasses. For that matter, there's no guarantee that a subclass would have the propery that it's trying to modify.

Secondly, why are you trying this indirect method for setting properties? Can't you just set the properties of the subclass the normal way? Or even just override your setProperties method in the subclass?

If you really want to set the properties from the superclass, what you can do though is have a method setsubProperties in the superclass that you then override in the subclass. You dispatch to this method from the setProperties method:

classdef Sup < handle %has to be a handle class to modify its own properties
    methods
       function setProperties(this, varargin)
           this.setsubProperties(varargin);
       end
   end 
     methods (Access = protected)
         function setsubProperties(this, varargin)
              error('function must be overriden');
         end
     end
  end
classdef sub < Sup
    methods (Access = proteced)
       function setsubProperties(this, varargin)
           for varg = 1:2:numel(varargin)
               %...
           end
       end
    end
 end

MATLAB: Suppressing superclass methods/events

This is the best you can do to hide the methods which are relared to handle (here superclass). All te methods are hidden except 'isvalid' which is a sealed method of 'handle' class.

classdef myClass < handle
    methods
        function O = myClass()
            
        end
    end
    methods (Hidden)
        function varargout = findobj(O,varargin)
            varargout = findobj@handle(O,varargin);
        end
        function varargout = findprop(O,varargin)
            varargout = findprop@handle(O,varargin);
        end
        function varargout = addlistener(O,varargin)
            varargout = addlistener@handle(O,varargin);
        end
        function varargout = notify(O,varargin)
            varargout = notify@handle(O,varargin);
        end
        function varargout = listener(O,varargin)
            varargout = listener@handle(O,varargin);
        end
        function varargout = delete(O,varargin)
            varargout = delete@handle(O,varargin);
        end
    end
end

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Related Solutions

MATLAB: Modifying an immutable/protected variable of a subclass in a superclass method

MATLAB: Suppressing superclass methods/events

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