How to remove the data from a handle class from memory

Question

Olaf Bousche 2015-8-5

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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/232442-how-to-remove-the-data-from-a-handle-class-from-memory

评论： Olaf Bousche 2015-8-13

采纳的回答： Ghada Saleh

在 MATLAB Online 中打开

I feel like an idiot but I don't seem to be able to solve the following problem:

When I define a handle class, how do I destroy it?

Example:

classdef test_class < handle
    properties
        % Lots of data
        data = rand(1e4,1e4);
    end
    methods
        function delete(obj)
            % What do I put here to destroy the object itself: erase the object itself from memory
            % Only "clear all" seems to work
        end
    end
end

Testing this with

x = test_class;
clear x
memory
clear all
memory

shows that the class data is effectively destroyed by clear all.

Does anyone know what code to use in the delete function ??

Thanks for you replies

Olaf

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Answer 1

Ghada Saleh 2015-8-7

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https://ww2.mathworks.cn/matlabcentral/answers/232442-how-to-remove-the-data-from-a-handle-class-from-memory#answer_188590

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Hello Olaf,

I understand you want to clear the class definition in the 'delete' method. You can use the following command:

clear classes;

Note that this command issues a warning and does not clear a class of objects if any of those objects still exists after the workspace is cleared. For example, objects can still exist in persistent variables of functions or figure windows. Also, lear classes does not clear a class if its file is locked using the mlock command. No warning is issued in this case.

Also, if you are using MATLAB R2012b or earlier versions, note that there is a bug when using clear classes. This bug is fixed in R2013a.

I hope this helps,

Ghada

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Olaf Bousche 2015-8-13

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Dear Ghada:

Thanks for your response. The clear classes provide only a partial solution for what I wanted. The problems I had with classes with a lot of data eating all my memory where caused by my misunderstanding on how to uses such classes. When you want to use such classes I should have created a class constructor. The following definition solves the problem:

classdef test_class < handle
    properties
        % Just the property
        data;
    end
    methods
        % Creator goes here
        function obj = test_class()
            obj.data = rand(1e4); % All the data
        end
    end
end