MATLAB: Is it possible to make objects of the same class listen to each other in MATLAB 7.7 (R2008b)

MATLAB

I have two instantiations of the same class. I want one instance to listen to the other instance. Is this possible?

Best Answer

Yes, it is possible to create two instances of the same class and set it up so that one listens to the other. The key is in how you define the instances.

If you define the instances 'a' and 'b' as follows, you are creating two different instances of type 'myclass', where 'b' listens to 'a'.

a = myclass;
b = myclass(a)

If you define the instances 'a' and 'b' as follows, you are creating one instance of 'myclass'. Any changes to 'b' will affect 'a', and vice versa.

a = myclass;
b = a;
b = myclass(a);

Please see the resolution document myclass.m for the class definition used in the above examples. Run the following example code to step through the class definition:

a = myclass;         % creates one instance of myclass
b = myclass(a);    % creates another instance of myclass that listens to 'a'
changestate(a,4);% changes the state of 'a' causing 'b' to react

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MATLAB: How to reorder cell array columns based on the order of a vector matrix, while keeping rows intact in Matlab

Would this work?

 >> buffer = arrayfun(@(rId) data(rId,order(rId,:)).', 1:size(order,1), ...
                      'UniformOutput', false) ;
 >> reordered_data = [buffer{:}].'
 reordered_data = 
    'B'    'B'    'B'    'B'    'B'    'A'    'A'    'B'
    'B'    'B'    'A'    'B'    'A'    'A'    'A'    'A'
    'A'    'A'    'B'    'A'    'A'    'B'    'B'    'B'
    'A'    'A'    'A'    'A'    'B'    'A'    'A'    'A'

MATLAB: Is calling a superclass constructor after a use of the object not allowed

I can only speculate as to why it would not be allowed, but I assume there are hazards in using an object that is not finished being constructed...like feeding a baby that is only half way through being born, or driving a car that’s only half assembled.

Below is how I would re-implement. In your original design, it doesn't make sense to me that the classB constructor should have to set x if it has already been set in classA.

classdef superclass
    
    %% PROPERTIES
    properties 
        x;
        y;
    end
    
end

classdef classA < superclass
    
    %% PROPERTIES
    properties
        a
    end
    
    properties (Access=private)
        z
    end
    
    %% METHODS
    methods
        % Constructor


        function obj = classA(a,z,y)
            obj.x = a*z;
            obj.a = a;
            obj.z = z;
            if nargin>2
             obj.y=y;   
            end
        end
    end
    
end

classdef classB < superclass
    
    %% PROPERTIES
    properties
        b
    end
    properties (Access=private)
        z
    end
    
    %% METHODS
    methods
        % Constructor
        function obj = classB(b,z,x)
            obj.y = z+b;
            obj.b = b;
            obj.z = z;
            if nargin>2
               obj.x=x; 
            end
        end
    end
    
end

classdef subclass < classA & classB
    
    %% METHODS
    methods
        % Constructor
        function obj = subclass(a,b,z)
            obj@classA(a,z);  %set x but not y
            obj@classB(b,z);  %set y but not x  
        end
    end
    
end

Best Answer

Related Solutions

MATLAB: How to reorder cell array columns based on the order of a vector matrix, while keeping rows intact in Matlab

MATLAB: Is calling a superclass constructor after a use of the object not allowed

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