MATLAB: How to determine if one class is superior or inferior to another

classMATLABoop

Matlab uses class precedence to determine which methods are called. Given two class names, is it possible to determine the class precedence relationship between the two? The new metaclass structure contains some of this information for classdef classes, but lacks information about older-style classes and fundamental types.

I'd love to find (or be able to write) a generic utility that simply asks is 'class_a' superior to 'class_b'? Is this possible?

Best Answer

Instead of having 2 class names, you can do it if you have 2 objects of the class using something like the function below. Moreover, if your class constructors all support the no-argument case, you could generate an object from a class name as follows

 obj=feval(className)

but I don't know if this would always be true for you.

function tf=issuperior(A,B)
%True if class(A) superior to class(B). Otherwise false.
    try
       stupidname_neverused(A,B);
    catch ME
    end
    name=strrep(ME.message,'Undefined function ''stupidname_neverused'' for input arguments of type ','');
     name=strrep(name,'''','');
     name(end)='';
    tf=strcmp(name,class(A));

Related Solutions

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

MATLAB: Super class get callers name

Found it. Just call this:

 me = class(obj);

this gives the name of the created subclass. I call it in the constructor of the superclass:

 function obj = mySuperClass() %constructor
   me = class(obj);
   obj.name = me;
 end

Best Answer

Related Solutions

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

MATLAB: Super class get callers name

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