Class property automatically propagated to old class instances

Dear matlab user,

I struggle with the following problem I have with my own definition for a class I use. I will illustrate the problem by means of an example. Say I define the following class:

classdef exampleClass

     properties
         exampleProp double {mustBeFinite(exampleProp)}
     end

     methods
        function obj = exampleClass(exampleProp)
           arguments
              exampleProp = []
           end

           obj.exampleProp = exampleProp;
        end
      end
end

Now I initiate a class instance as follows:

Exmp = exampleClass(1);

I have the following issue when I copy the object.

Exmp1 = exmp;

Exmp2 = exmp;

Exmp1.exampleProp = 5;

What I would like to happen is that Exmp1 is updated and Expm,Expm2 are unchanged. However all objects now have that the exampleProp property is changed to 5. How do assure that I can change a property value without it being propagated to other class instances?

Thanks you very much!

Answer 1

[per isakson]

See Comparison of Handle and Value Classes

Your exampleClass is a value class. However, the behavior you describe is more like that of a handle class. See the examples below. (To run the code I need to attach the classdef-files rather than including them in this text.)

%%  value class
v  = exampleClass(1);
v1 = v

v1 = 
  exampleClass with properties:

    exampleProp: 1

v2 = v

v2 = 
  exampleClass with properties:

    exampleProp: 1

v1.exampleProp = 5

v1 = 
  exampleClass with properties:

    exampleProp: 5

v

v = 
  exampleClass with properties:

    exampleProp: 1

v2

v2 = 
  exampleClass with properties:

    exampleProp: 1

%%  handle class
h  = exampleClass_handle(1);
h1 = h

h1 = 
  exampleClass_handle with properties:

    exampleProp: 1

h2 = h

h2 = 
  exampleClass_handle with properties:

    exampleProp: 1

h1.exampleProp = 5

h1 = 
  exampleClass_handle with properties:

    exampleProp: 5

h

h = 
  exampleClass_handle with properties:

    exampleProp: 5

h2

h2 = 
  exampleClass_handle with properties:

    exampleProp: 5

[Luuk Spin]

Thanks a lot! Indeed the class inherited properties from a superclass that inherited the handle class. I changed the superclass and now it works :)