Static methods are unnecessary, right?

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fa wu on 9 Aug 2023

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https://nl.mathworks.com/matlabcentral/answers/2006482-static-methods-are-unnecessary-right

Edited: James Tursa on 8 Dec 2023

I researched static methods and feel that static methods are non-essential in matlab.There would be no inconvenience if matlab did not provide a static method.I wonder if my above opinion is correct?

The benefit of static methods is "not related to the specific object", only related to classes.Can be called inside the class.Also can be called by the object！

I found I can do what the static method does with ordinary methods！

Here's a simple example.method1 didn't use input argument. I can use method1 in constructor.Although the program uses 'obj.method1' to call method1, this does not mean that method1 is related to any specific object.

classdef test<handle
    properties
        X
        Y
    end
    
    methods
        function obj = test(inputArg1,inputArg2)
            obj.X = inputArg1 + inputArg2;
            obj.Y=obj.method1(inputArg2);
        end
    end
    methods
        function value = method1(obj,inputArg)
            value = 3 + 3;
        end
    end    
end

Here's a more complex example.Use object-oriented programming method to draw three-dimensional surface graph. It is required to define two classes, one of which stores the data of the function, and uses a static method to calculate the grid coordinates of the interval in this class; the function of the other class is to draw a three-dimensional surface map, and the drawing process is realized by a static method.

@MfunEval/MfunEval.m

 classdef  MfunEval
        properties
          HFun;    
          Lm = [-2*pi 2*pi];     
        end
        properties (Dependent = true)
          Data;          
        end
        methods
           function obj = MfunEval(fun_handle,limits)   %Constructor
               obj.HFun = fun_handle;
               obj.Lm = limits;
           end
           function data = get.Data(obj)      %
             [x,y] = MfunEval.grid(obj.Lm);  
             z= obj.HFun(x,y);
             data.X = x;
             data.Y = y;
             data.Z = z;
           end
        end
        methods (Static)      %Static methods
           function [x,y] = grid(lim)   
                step = (lim(2)-lim(1))/50;
               [x,y] = meshgrid(lim(1):step:lim(2));
           end
        end
    end

@MfunView/MfunView.m

classdef MfunView
        properties
          FunObj          
          HSurf           
        end
        methods
           function obj = MfunView(fobj)  %Constructor
             obj.FunObj= fobj;
           end
        end  
        methods (Static = true)           %
            createViews(a)                %
        end  
    end    

@MfunView/ createViews.m

 function  createViews(funevalobj)
      viewobj=MfunView(funevalobj);
      viewobj.HSurf = surf(viewobj.FunObj.Data.X,...
          viewobj.FunObj.Data.Y,...
          viewobj.FunObj.Data.Z);
      shading interp;
    end    

I modified @MfunEval/MfunEval.m Replaced MfunEval.grid with obj.grid.I change the static method to a normal method. The program can still run!

classdef  MfunEval
    properties
        HFun;    
        Lm = [-2*pi 2*pi];    
    end
    properties (Dependent = true)
        Data;          
    end
    methods
        function obj = MfunEval(fun_handle,limits)   %Constructor
            obj.HFun = fun_handle;
            obj.Lm = limits;
        end
        function data = get.Data(obj)      
            %[x,y] = MfunEval.grid(obj.Lm);
            [x,y] = obj.grid(obj.Lm);  %call grid function
            z= obj.HFun(x,y);
            data.X = x;
            data.Y = y;
            data.Z = z;
        end
    end
    methods %(Static)      %change Static
        function [x,y] = grid(obj,lim)    
            step = (lim(2)-lim(1))/50;
            [x,y] = meshgrid(lim(1):step:lim(2));
        end
    end
end    

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James Tursa on 10 Aug 2023

Cross-posted here:

https://stackoverflow.com/questions/76872102/matlab-static-methods-are-unnecessary-right

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Answer 1

James Tursa on 8 Dec 2023

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https://nl.mathworks.com/matlabcentral/answers/2006482-static-methods-are-unnecessary-right#answer_1368124

Edited: James Tursa on 8 Dec 2023

I use Constant Properties and Static Methods all the time in classes I am creating. In particular, when I am developing a group of functions that are all interrelated I will create a class to hold them all. Creating an object of this class is an unnecessary step since all methods are designed to be called using the class name directly. The constant properties can be accessed in the same manner. In fact, creating an object of this class serves no purpose since the class has no properties that are non-constant. I find Static Methods a very useful feature.