How to change the default Value of superclass property in subclass

Is there any way to change the default value of a super class property in the property block of a subclass? I know I can change it in the constructor method, but the semantics of that doesn't seem right. Also making the property abstract in the super class is inconvenient because then you can't really directly instantiate the superclass. is there any solution to this?

[Matt J]

Elaborate on the circumstances in which this change would be made. Otherwise, I could answer "just edit the classdef file".

[Nicholas Dinsmore]

That is what I mean in the classdef file. To elaborate for example in the superclass I have a property CalculationMode=1; which is effectively and option used by a method of the superclass. Now in the sub class I want the value of CalculationMode=2; so that the superclass method that does the calculating uses its no default Calculation mode. Now I know I can change that volume in the sub class constructor, but there are many properties that have the same situation and changing them in the sub class constructor seems like less readable/obvious code. Does that make sense?

[Daniel Shub]

No, it doesn't make sense. Please provide the code for a simple superclass and subclass and explain what you want to do with that code. Please edit the original question to include the code and don't post it as a comment.

[Matt J]

Also explain what you mean by "I know I can change it in the constructor method, but the semantics of that doesn't seem right." I don't see how there could be anything semantically wrong with setting the value in the constructor. It seems like the most natural thing to do.

[Nicholas Dinsmore]

This is what I would like to do

   classdef superclass < handle
        properties
          CalculateMode=1; %1=option1  2=option2
        end
   end
   classdef subclass < superclass
        properties
          CalculateMode=2;
        end
   end

Answer 1

[Matt J]

Abandon this and set the value of CalculateMode in the constructor. It's the appropriate thing to do.

Answer 2

[Philip M]

Overriding a superclass property with a subclass property involes a few hurdles, but overwriting a superclass method with a subclass property is simple. This allows the superclass to define a set of defaults, and allows the subclasses to modify those defaults without requiring the subclasses to repeat the same lines of code in each constructor.

The concept in its absolute simplest form:

classdef Super
    properties
        CalculateMode
    end
    methods
        function obj=Super
            obj.CalculateMode=obj.CalculateModeSetting;
        end
        function out=CalculateModeSetting(~)
            out=1;
        end
    end
end

classdef Sub < Super
    properties
        CalculateModeSetting=2
    end
end

Which gives:

>> Super
ans = 
  Super with properties:

    CalculateMode: 1
    
>> Sub
ans = 
  Sub with properties:

    CalculateModeSetting: 2
           CalculateMode: 2

Answer 3

[Daniel Shub]

The only other way I can think to do this is to have the superclass constructor take an CalculateMode as an optional argument. Then the subclass constructor would pass the mode to the superclass.