Namespace not recognized when used in a function called from an app

I have an app that calls a function in an external file. The function references a class in a namespace directory (beginning with a +). I set up the paths in the app to include the namespace directory's parent folder and not the namespace directory. When the app calls the function, the function generates a MATLAB:UndefinedFunction error that it cannot locate the namespace.class. When I debug I stop at the problematic line and can access the namespace as normal in the debug command line. I can execute the code of the line where the error occurs, but if I click continue in the debugger the code fails.

Simplified example code:

MyProject/
  +MyNameSpace/
     MyClass.m
  MyApp.mlapp
  MyFunction.m
  startup.m

MyClass.m:

classdef MyClass
    properties (Constant)
        value = 1;
    end
end

MyFunction.m:

function value = MyFunction()
    value = MyNameSpace.MyClass.value;
end

startup.m:

function startup
    % Determine where your m-file's folder is.
    folder = fileparts(which(mfilename));
    % Add that folder plus all subfolders to the path.
    addpath(folder);
end

Then inside the MyApp.mlapp I use the startupFcn method that is called by the constructor to call startup.m:

        function startupFcn(app)
            startup
        end

And a button callback to call MyFunction:

        % Button pushed function: RunButton
        function RunButtonPushed(app, event)
            value = MyFunction();
        end

The returned error states:

"Unrecognized function or variable 'MyNameSpace'."

Answer 1

[Taylor]

If value never changes you can just make it constant

classdef MyClass
    properties (Constant)
        value = 1;
    end
end

Otherwise, you can create an instance of the class to access its properties

function value = MyFunction()
    obj = MyNameSpace.MyClass();
    value = obj.value;
end

[Mat]

In actual fact it is a constant! I forgot to put that in the example code. I am using the namespace to contain classes that contain different types of constant. However, this doesn't affect the underlying problem of accessing the namespace from a function called from an app.