What's the best way to prevent a class from being instantiated?

Question

埃博拉酱 2022-2-23

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https://ww2.mathworks.cn/matlabcentral/answers/1656465-what-s-the-best-way-to-prevent-a-class-from-being-instantiated

评论： Steven Lord 2022-2-24

I want this class to be completely static and can never be instantiated. It only contains a bunch of static methods and constants.

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Answer 1

Steven Lord 2022-2-23

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https://ww2.mathworks.cn/matlabcentral/answers/1656465-what-s-the-best-way-to-prevent-a-class-from-being-instantiated#answer_902655

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Make it Abstract.

classdef (Abstract) purelyStatic
    methods(Static)
        function y = getPi()
            y = pi;
        end
    end
    properties(Constant)
        theAnswerToLifeTheUniverseAndEverything = 42;
    end
end

Use it as:

P = purelyStatic.getPi()
A = purelyStatic.theAnswerToLifeTheUniverseAndEverything

Trying to instantiate it will error.

x = purelyStatic

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埃博拉酱 2022-2-24

It's just abstract. It can be inherited and then instantiated.

Steven Lord 2022-2-24

在 MATLAB Online 中打开

Make it Sealed as well. That still wouldn't prevent someone from editing the class file but there isn't really a way to make it so it can never, ever, ever be modified. At least not while butterflies exist :)

classdef (Abstract, Sealed) purelyStatic

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