MATLAB: Property validation in subclass

inheritanceooppropertysubclassvalidation

Hello everyone, i am new to the OOP in Matlab.
I have a superclass SimpleList with the property set, which is an array with any kind of data in it.
 classdef SimpleList < handle
    % SimpleList
    properties
        set(:,1)
    end
    methods
     .
     .
     .
    end
 end
And a subclass ObjList, where the array should only contain objects of a specific class
 classdef ObjList < SimpleList
    % ObjectList
    properties
    end
    methods
     .
     .
     .
    end
 end
My Question is: How do i validate the property in ObjList?
Thanks in advance!

Best Answer

Note: I would recommeng giving a name other than set to your property. That name is already overloaded enough by matlab.
You can create a property validation function in the class that define the property using the syntax (for handle classes):
function set.propertyname(object, valuetoset)
    %validation code
end
with your property name this would be
function set.set(this, value)     %See why you should rename the property?
   if ~strcmp(class(value), somevalidclass)
        error('invalid class supplied to set');
   end
   this.set = value;
end
However, as I said, this property set method must be implemented in the class that defines the property, that is your base class, not the derived class. The workaround is from the set method to call another method that does the validation and is overridden by the derived class:
classdef SimpleList < handle
    properties
        set;
    end
      methods
          function set.set(this, value)
              isok = this.validateset(value);  
              if ~isok
                 error('invalid type of variable for set property)
              end
              this.set = value;  %DO NOT set the value is a subfunction or you'll get infinite recursion
          end
      end
      methods (Access = protected)
          function isok = validateset(this, value)
             isok = true;
          end
      end
  end
classdef ObjList < SimpleList
    methods (Access = protected)
        function isok = validateset(this, value)
           isok = strcmp(class(value), 'double');
        end
    end
end
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