Global Static classes (or alternative?)

Hi there,

I am writing a fairly large script in Matlab 2010b that depends heavily on objects. Most of these objects have methods and properties, a few contain other objects.

What I want is to be able to manipulate some variables and objects from anywhere in my code. Due to the strict scope of variables in Matlab, the only way to do this is by passing the variables I might want to read/edit between every method. This can get very cumbersome indeed, expecially if I have a few objects and data I need accessed.

Two examples of this might be:

• A logging output file handle. I open a file handle right at the start of my script. I want all the methods in all the objects to write to this log file. At the moment, I pass the file handle by reference deep into the bowels of my code. Technically correct, but very ugly
• A 'database' object that contains a set of data that is read by a number of methods. This is an object now but could equally be a matrix (there are no methods). Again, if I want to read this data, I need to pass it deep into my object tree manually.

What I was hoping for was some manner of global (possibly static) object. I would set these up at the start of my script and have them readable/writable from any point in my code, even if the variable scope changes. It's not good practice, but for my purposes I reckon it will be safe enough.

However, global variables don't appear to persist between scope changes and global vars I declare (even primitives) are not accessible once the scope changes. Should this be the case?

Is there a better way to do this?

Thanks!

Answer 1

[Joan Puig]

Hi Alexander,

I think you could try to use this inside your class definition:

    methods (Static)
        function singleton = getInstance
             persistent local
             if isempty(local)
                local = ... Initialize your variable
             end
             singleton = local;
        end
    end

Because it is a static method it can be used from anywhere in the code just by typing

    MyClass.getInstance();

On a side note, MyClass should probably inherit from handle.