What is the correct way to update super class properties?

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I have a class which serves as a data class for objects with the same pattern. In my example I will use a class Surface:
% Surface.m
classdef Surface
properties
area
circumference
end
methods
function obj = Surface(area, circumference)
obj.area = area ;
obj.circumference = circumference ;
end
end
end
Now there are different methods to construct a so called Surface class and since I cannot define multiple constructors for Surface in Matlab I create subclasses which are all of the type Surface, in my example a class Circle.
% Circle.m
classdef Circle < Surface
properties
r
end
methods
function obj = Circle(r)
obj@Surface(0, 0)
obj.r = r ;
obj.area = pi * r^2 ;
obj.circumference = 2 * pi * r ;
end
end
end
Now I want a object of type circle to update its superclass properties when its properties are changed. How can I solve this? If the property would be in the class itself I would use a dependent property, but what is the correct pattern, if the property is in a superclass?
% test_classes.m
function tests = test_classes
tests = functiontests(localfunctions);
end
function test_surface(~)
area = 2 ;
circumference = 3 ;
s = Surface(area, circumference) ;
assert(s.area == area) ;
assert(s.circumference == circumference) ;
end
function test_circle(~)
r = 2 ;
area = pi * r^2 ;
circumference = 2 * pi * r ;
c = Circle(r) ;
assert(c.area == area) ;
assert(c.circumference == circumference) ;
end
function test_cicle_change_property(~)
% Change circle property THIS WILL FAIL
c = Circle(2) ; % Create Class
c.r = 6 ; % changed property
r = 6 ; % update test values.
area = pi * r^2 ; % update test values.
circumference = 2 * pi * r ; % update test values.
assert(c.area == area) ; % <-- how do I fix this?
assert(c.circumference == circumference) ;
end

Answers (1)

Prince Kumar
Prince Kumar on 31 Mar 2022
Hi,
Please refer to the following documentation
It has been clearly explained here.
Hope this helps!

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