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POHow to clear a persistent variable in a MATLAB method
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copied!<p>I have a MATLAB class that contains a method that employs a persistent variable. When certain conditions are met I need to clear the persistent variable without clearing the object to which the method belongs. I've been able to do this, but only by employing <code>clear functions</code> which has excessively broad scope for my purposes.</p> <p>The classdef .m file for this problem:</p> <pre><code>classdef testMe properties keepMe end methods function obj = hasPersistent(obj) persistent foo if isempty(foo) foo = 1; disp(['set foo: ' num2str(foo)]); return end foo = foo + 1; disp(['increment foo: ' num2str(foo)]); end function obj = resetFoo(obj) %%%%%%%%%%%%%%%%%%%%%%%%% % this is unacceptably broad clear functions %%%%%%%%%%%%%%%%%%%%%%%%% obj = obj.hasPersistent; end end end </code></pre> <p>A script that employs this class:</p> <pre><code>test = testMe(); test.keepMe = 'Don''t clear me bro'; test = test.hasPersistent; test = test.hasPersistent; test = test.hasPersistent; %% Need to clear the persistent variable foo without clearing test.keepMe test = test.resetFoo; %% test = test.hasPersistent; test </code></pre> <p>The output from this is:</p> <pre><code>>> testFooClear set foo: 1 increment foo: 2 increment foo: 3 increment foo: 4 set foo: 1 test = testMe Properties: keepMe: 'Don't clear me bro' Methods </code></pre> <p>which is the desired output. The problem is that the line <code>clear functions</code> in the classdef file clears all functions in memory. I need a way to clear with a much smaller scope. For example, if <code>hasPersistent' was a function instead of a method, the appropriately scoped clear statement would be</code>clear hasPersistent`.</p> <p>I know that <code>clear obj.hasPersistent</code> and <code>clear testMe.hasPersistent</code> both fail to clear the persistent variable. <code>clear obj</code> is similarly a bad idea.</p>

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