MATLAB Object-Oriented Programming

Initialize Arrays of Handle Objects

When initializing an array of handle objects, MATLAB fills in the empty elements of an

array with a default object. To create the default object, MATLAB:

• Calls the class constructor once to obtain an object


• Creates unique handles for each element in the array


• Copies the property values from the constructed default object without calling the
  constructor again.

The InitHandleArray class illustrates this behavior.

classdef InitHandleArray < handle

properties

RandNumb

end

methods

function obj = InitHandleArray

obj.RandNumb = randi(100);

end

end

end

The property RandNumb contains a random number that the InitHandleArray

constructor assigns.

Consider what happens when MATLAB initialize an array created by assigning to the last

element in the array. (The last element is the one with the highest index values). Suppose

the value of the RandNumb property of the InitHandleArray object assigned to the

element A(4,5) is 59 :

A(4,5) = InitHandleArray;

A(4,5).RandNumb

ans =

59

The element in the index location A(4,5) is an instance of the InitHandleArray class.

The default object used for element A(1,1) is also an instance of the InitHandleArray

class, but its RandNumb property is set to a different random number.

Initialize Arrays of Handle Objects 10-