Resizing array of handle objects

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Luca Ferroglio
Luca Ferroglio 2022-12-19
回答： Rik 2022-12-19
Hi all,
I'm trying to define a handle object, which is (potentially) an array of objects, and I'm trying to define a method to successfully resize it.
classdef anArrayObject < handle
properties (Access = public)
prop = 0 % just a dummy property
end
methods
% this initializes my array of handle objects
function obj = anArrayObject(n)
if nargin ~= 0
validateattributes(n, {'numeric'}, {'scalar', 'integer' 'positive'});
for i = 1:n
obj(i).prop = i; % Expands the object to become an array of the size n
end
end
end
% Here I'd like to resize my array on demand, but this does not work.
% Any way to resize this array?
function obj = resizeMe(obj, m)
validateattributes(m, {'numeric'}, {'scalar', 'integer' , 'positive'});
if m < numel(obj)
obj = obj(1:m);
end
end
end
end
As from comments in the code: I can successfully crate the array of objects, but the resizeMe function does not do what I want.
myObjArray = anArrayObject(5);
numel(myObjArray)
ans = 5
myObjArray.resizeMe(3);
numel(myObjArray)
ans = 5
Any way to resize this handle object?

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回答（1 个）

Rik
Rik 2022-12-19
Ran in:
The problem is that while your object array is an array of handles, it isn't a handle variable itself. What that means is that you have an array of 5 handle objects, which you then shorten to 3:
myObjArray = anArrayObject(5)
myObjArray =
1×5 anArrayObject array with properties: prop
myObjArray.resizeMe(3)
ans =
1×3 anArrayObject array with properties: prop
Notice with the last result that the initial variable is not actually modified.
The solution I can think of would be to store the array inside the object, instead of exposing it as a normal array. You can probably overlead subsref to get most of the behavior of an array.

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