Editing superclass properties from subclasses

Hi!

I have a question related to the Matlab example http://www.mathworks.com/help/matlab/matlab_oop/a-simple-class-hierarchy.html. For testing I use:

ds = DocSavings;
db = DocBond;

I can change the superclass property "Description" with

ds.Description = 'test';

However, listing "db" properties shows an empty "Description" string. Is there a way to synchronize superclass properties? Is using events and listeners of handle classes the only possible way?

Maybe: Another way is to use the subclasses as normal classes and define objects of these classes as properties of the former superclass?

Is there a better solution?

Answer 1

[per isakson]

Why do you want different objects to share ( "synchronize" ) property values? However, without looking at the documentation you refer to.

    super = SuperClass;
    sub = SubClass;
    sub.handle.Description = 'Hello';
    super.handle.Description
    super.handle.Description = 'World';
    sub.handle.Description

returns

    ans =
    Hello
    ans =
    World

where

    classdef   SuperClass < handle
        properties
            handle = DescriptionContainer();
        end
    end

and

    classdef   DescriptionContainer < handle
        properties
            Description
        end
    end

and

    classdef    SubClass < SuperClass
        properties
            another_property
        end
    end

.

With the help of a dependent property together with set and get methods, I think it would be possible to hide (Access=protected) the property, which I call "handle".

.

The word, "Editing", in the subject line makes me unsure regarding your intent.

"Maybe: Another way ..." sounds strange to me. Wouldn't that overly complicate the dependencies.

"events and listeners" if nothing else it complicates the debugging.

[Simon]

Hi!

Thank you for your reply!

"Editing" in the subject line maybe better replaced with sharing or synchronizing, you're right.

Why do you want different objects to share ( "synchronize" ) property values?

Suppose I have a superclass for reading/writing to a file, with a property called "FileName". If I create two subclasses to use this superclass, each subclass has its own instance of the superclass property "FileName". But I want to write the individual properties of the subclasses to the same file (automatically). This is true if I have another class (like in your example) storing the filename (the description in your example). This is the second solution I tried to explain in my "Maybe: Another way ..." paragraph. But I realize it was quite confusing ;-)

I think I should re-think the problem ...

[per isakson]

Comments:

• What you describe makes me think of a logger. See the FEX-contributions log4m and log4matlab
• Make some experiments with running code before you settle for a solution.
• "Is there a better solution?" I think the solution I outline answers your question.