Updating property of an Object without creating new object

Hi

I’m writing a class for the first time, and got an issue I don’t understand.

To simplify the problem, assume my class is as follows:

    ========================================

    classdef testClass

        properties
            count
        end

        methods
            function obj = testClass
                obj.count = 1;
            end

            function obj = increment(obj)
                obj.count = obj.count + 1;
            end
        end

    end

    ========================================

    >> x = testClass;

This creates the class and sets x.count to 1 as required

I then want to increment the value of x.count I was hoping that:

    >> x.increment;

would add 1 to count. But it simply creates a new object (‘ans’), where ans.count == 2

I can of course write,

    >> x = x.increment;

But that feels illogical.

I've tried various things, and Googled the type of problem, but have found a solution. So any guidance would be welcome.

Thanks.  Martyn

[Dr. ghada farouk]

you should write

x=x.increment(x);

[Walter Roberson]

Dr. ghada farouk: writing that is not needed if you use a handle class.

Answer 1

[Sebastian Castro]

When you create a class in MATLAB, it is by default a value class. If you want to update objects by reference, you should make this a handle class by changing the first line to:

classdef testClass < handle

EDIT: Also, you wouldn't necessarily need output arguments for the methods of the handle class.

Check out this documentation page for the differences between value classes and handle classes.

- Sebastian

[Martyn]

Thanks Sebastian, that works as I was planning.

I'll read through the documentation in more detail ... just a lot learn! Thanks again

[MosGeo]

Awesome! I didn't know this bit. It was driving me insane coding in that weird way.

[Redouane Bouchou]

Thank you

[Arvind]

thanks a lot.