Number of input parameters in Superclass method

I'm a total newbie to OOP and I'm trying to compute a full factorial design depending on the number of input parameter (e.g. speed, distance, time). My superclass does only consider speed, therefore this speed array would be my full factorial design, but in my subclasses i would like to add more parameters (for example distance and time) therefore my design would be a x-by-3 array. I would like to implement the DOE computations only once in the superclass and not in every subclass.

classdef Superclass
     properties
        speed
        params
        doe
        prop1
     end
    methods
        function obj = Superclass(speed)
            obj.speed = speed;
            obj.params = {'speed'};
        end
        function obj = computeDoe(obj)
            % Get number of parameters for speed, distance, time and so on
            for i = 1:numel(obj.params)
                numParams(i) = numel(obj.(obj.params{i}));
            end
            % Create full factorial design by number of parameters 
            ff = fullFactorial(numParams);
            % Compute DoE
            for i = 1:numel(obj.params)
                obj.doe(:,i) = obj.(obj.params{i})(ff(:,i));
            end
        end
    end
end

classdef Subclass < Superclass
    properties
        distance
        time
        prop2
    end
    methods
        function obj = Subclass(speed, distance, time)
           obj@Superclass(speed)
           obj.distance = distance;
           obj.time = time;
           obj.params = {'speed', 'distance', 'time'};
        end
    end
end

superClassObj = Superclass([1 2 3])
superClassObj.computeDoe;
superClassObj.doe

subClassObj = Subclass([1 2 3], 4:7, [0.1 0.2])
subClassObj = subClassObj.computeDoe
subClassObj.doe

I need to know in my computeDoe method how many parameters I have for creating my doe design, how can i do that without saving the involved parameters on my obj.params property? My code works but i doubt that this is a good solution...i don't really know which kind of OOP mechanism to apply on this right now. If i use for example an Abstract Class, i have to implement the computeDoe method in every subclass or am I completely wrong? Thanks a lot for your help!

Answer 1

[Matt J]

My design would be as below.

classdef Superclass
     properties
        params %now a struct
        doe
        prop1
     end
    methods
        function obj = Superclass(speed)
            obj.params.speed = speed;
        end
        function obj = computeDoe(obj)
            % Get number of parameters for speed, distance, time and so on
            
            numParams=structfun(@numel,obj.params);
            
            paramNames=fieldnames(obj.params);

            % Create full factorial design by number of parameters 
            ff = fullFactorial(numParams);
            % Compute DoE
            for i = 1:numel(paramNames)
                obj.doe(:,i) = obj.(obj.params.(paramsNames{i})  )(ff(:,i));
            end
        end
    end
end

classdef Subclass < Superclass
    properties
        prop2
    end
    methods
        function obj = Subclass(speed, distance, time)
            obj@Superclass(speed)
            obj.params.distance=distance;
            obj.params.time=time;
        end
    end
end

[Matt J]

If you don't want to go through the params member to access your parameters, you can use Dependent properties or overloaded subsref/subsasgn methods to define shorthands, e.g.,

classdef Superclass
     properties
        params %now a struct
        doe
        prop1
     end
    methods
        function obj = Superclass(speed)
            obj.params.speed = speed;
        end
        function obj = computeDoe(obj)
            % Get number of parameters for speed, distance, time and so on
           ....
        end
        
        
        function val=subsref(obj,S)
           
            if S(1).type=="." && ismember(S(1).subs, fieldnames(obj.params))             
                val=builtin('subsref',obj.params,S);
            else
               val= builtin('subsref',obj,S);
            end
            
        end
        
    end
end

[Jens Gaechter]

Yes using a struct for saving my involved parameters instead of using a separate property makes completely sense. I will also check out your suggestion via subsref - thanks a lot Matt!