Object array: modify properties of a single element

I'll try to be short.

I have the class "testClass" defined in this way:

classdef testClass<handle
  properties
      value=[];
  end
  methods
      function modifyValue(input,number)
         input.value=number;
      end
  end
end

Then, in the command window I write:

>>MyClass(1:10)=testClass;
>>MyClass(1).modifyValue(10);

The idea is to create an array of objects (made of, in this case, 10 elements). With the second line command I'd like to modify only the property ("value") of the first element of the array "MyClass", leaving the properties of the other elements "MyClass(2:end)" unchanged.

I get the following:

>> MyClass(1)

ans = 

    testClass with properties:

      value: 10

>> MyClass(2)

ans = 

    testClass with properties:

      value: 10

[...]

the property "value" is set equal to 10 for all the elements of the array "MyClass". How can make it work in the intended way? (e.g. "MyClass(1)" having a property "value" equal to 10 while "MyClass(2)" equal to [])

Thank you for your help and sorry for my bad english.

Answer 1

[per isakson]

This is a bit tricky. You have created an array of ten object handles to the same underlying object. Thus, a change of the value of the property, value, by means of one handle can be referred to by all ten handles.

One way to create an array of ten different objects is

MyClass = testClass.empty(1,0);
for jj = 1 : 10
    MyClass(jj) = testClass;
    MyClass(jj).modifyValue(jj*10);
end

and inspect the property values

>> [MyClass.value]
ans =
    10    20    30    40    50    60    70    80    90   100

And there are other more elegant ways, see Initialize Arrays of Handle Objects and Construct Object Arrays