How to set a private property

Ok so I'm used to c++, and in c++ a private variable (property in matlab) can be accesed by every method in that class, I'm trying to do the same here in the constructor, I want it to establish some default values if no arguments have been provided, this is my code:

classdef modulo
    properties (Access=private)
        A
        B
        R
        actuadores
    end
    methods
        function obj=modulo(BB,Actuadores)
            if nargin<1
                obj.B=[0,0,0];
            end
            if nargin<2
                obj.actuadores=0;
            else
                obj.B=BB;
                obj.actuadores=Actuadores;
            end
        end
    end
end

But then, I do

smth=modulo

or

smth=modulo([4 3 2],5)

and I expect:

smth = 

    modulo with properties:

               A: []
               B: [0 0 0]
               R: []
      actuadores: 0

or

smth = 

    modulo with properties:

               A: []
               B: [4 3 2]
               R: []
      actuadores: 5

But instead I get:

smth = 

    modulo with no properties.

It works as intended when I don't set any private attributes, but how can I access those properties if I want them to be private?

Answer 1

[Walter Roberson]

https://www.mathworks.com/help/matlab/matlab_oop/property-attributes.html

Look at the description of Access:

"Use Access to set both SetAccess and GetAccess to the same value. "

So setting Access to private sets GetAccess to private.

Then in the description of GetAccess:

"MATLAB does not display in the command window the names and values of properties having protected or private GetAccess or properties whose Hidden attribute is true."

Therefore what you are seeing is the designed behavior for having set Access to 'private': you have told it not to display those properties when the object is displayed.

[Walter Roberson]

You cannot access the properties from outside (including the command line) if you set them to be private. That's what it means to be private.

If you need to look at them for debugging purposes, then you can struct() the object.

[Javi Cansa]

Oh I see, thank you!

So if I understood correctly, the object is not actually empty, it's just that I can't see it's contents due to them being private? So if I use them in some other method it'll work, right? (like, for example, some "get" function).

(Thank you again)

[Walter Roberson]

Right, you just cannot see the properties from outside the class objects. You cannot get() private properties from outside the class objects either. From outside the class objects all you can do is bypass the security by using struct() to look at the properties.

[Javi Cansa]

Thank you, I simply created a get method myself for debug purposes, so whenever I want to see, say, B for example, I just write:

smth.get('B')

and it returns whatever is stored in B.