Why do we need to use dynamic properties?

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fa wu 2023-9-5

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https://ww2.mathworks.cn/matlabcentral/answers/2017171-why-do-we-need-to-use-dynamic-properties

评论： fa wu 2023-9-7

Why do we need to use dynamic properties? In what situations must we use dynamic properties? What value do they bring? If I must add a property, why not add it within the class instead of adding a dynamic property to the object?

The book I'm reading provides examples of dynamic properties, but I find that they seem to function like regular variables. Furthermore, it seems like this program can achieve its goals without dynamic properties. Please take a look at the code below.

classdef  MyButton < dynamicprops
    properties
        UiHandle
    end
    methods
        function obj = MyButton(pos)
            if nargin > 0
                if length(pos) == 4
                    obj.UiHandle = uicontrol('Position',pos,...
                        'Style','pushbutton');
                else
                    error('Improper position')
                end
            end
        end
    end
end

The book instructs to execute the following commands.

hbutton1 = MyButton ([20 40 100 40]);   
addprop(hbutton1,'Caption');  
hbutton1.Caption='OK';
set(hbutton1.UiHandle,'String',hbutton1.Caption)

However, I found that removing dynamic properties does not affect the outcome.

hbutton1 = MyButton ([20 40 100 40]);
hbutton1.UiHandle.String='OK'

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fa wu 2023-9-6

@Stephen23 I feel that you must have appreciated the advantages of dynamic properties. I'm looking forward to you providing a formal answer with example code.

fa wu 2023-9-7

@Stephen23 Does this example fit the situation you mentioned? -------“I often create GUIs where objects (uicontrols, axes, etc) get switched between various states (particularly visibility, view, string, etc) depending on other menu/data selections).”

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回答（1 个）

Matt J 2023-9-6

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https://ww2.mathworks.cn/matlabcentral/answers/2017171-why-do-we-need-to-use-dynamic-properties#answer_1302416

They are a convenience, not a requirement. From the documentation:

Use dynamic properties to attach temporary data to objects or to assign data that you want to associate with an instance of a class, but not all objects of that class.

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fa wu 2023-9-6

Why doubt it--------I don't doubt, I don't undstand.

"Use dynamic properties to attach temporary data to objects or to assign data that you want to associate with an instance of a class, but not all objects of that class."--------It tell me How,don't tell me Why.

Matt J 2023-9-6

Well, like I said, it's just so that you can attach data to an object without cluttering the classdef with additional properties that you're only going to use for one application. I don't think there's any more to it than that.

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