Does the access method of a dependent property get called twice when the property is indexed into?

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Naor Movshovitz 2016-10-13

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https://ww2.mathworks.cn/matlabcentral/answers/307052-does-the-access-method-of-a-dependent-property-get-called-twice-when-the-property-is-indexed-into

回答： Naor Movshovitz 2016-10-13

采纳的回答： Naor Movshovitz

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I have a class with a dependent property z. The method get.z(obj) returns a vector. This:

y = myObj.z(end);

appears to call get.z twice! The profiler shows 2 calls from the parent function and the run time is twice the expected run time. On the other hand:

x = myObj.z;
y = x(end);

calls get.z once and cuts down run time by half. Is this the intended behavior?

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Walter Roberson 2016-10-13

I speculate that one of the two is due to the "end", as it would need to find the size . This is just speculation on my part, though.

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Answer 1

Naor Movshovitz 2016-10-13

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Confirmed Walter's comment. Indeed the culprit is the keyword end. Here is minimal working example.

classdef Untitled
    properties (Dependent)
        x;
    end
    methods
        function val = get.x(~)
            fprintf('called\n')
            val = [1,2,3];
        end
    end
end
>> obj = Untitled;
>> obj.x(2);
called
ans =
       2
>> obj.x(end)
called
called
ans =
       3