MATLAB: Implementing an hgsetget subclass

classhsetgetmatlab oopset

I would like to create a subclass of hgsetget that would show this kind of behavior:
>>u=unit('SI');
>>set(u)  % set behavior 1
  System: '[{SI} | cgs]'
>>set(u,'System') % set behavior 2
  [{SI} | cgs]
>>set(u,'System','cgs')  % set behavior 3
>>get(u,'System')
    ans =
    cgs
In other words, much like the behavior you see for a figure handle. Following the example in Implementing a Set/Get Interface for Properties, I tried this code:
classdef unit < hgsetget
    properties
        System = '';
    end
    methods
        function H = unit(str)
            if nargin > 0
                H.System = str;
            end
        end
        function H = set.System(H,str)
            H.System = str;
        end
    end
end
This gets set behavior 3 right, but how do I add the other two? The closest I have come so far is to simply program all the cases into an overloaded set method, and get rid of set.System. But if I add a few more properties, this gets quite ugly. Does anyone know an elegant way of doing this?

Best Answer

O.k., this works:
classdef unit < hgsetget
% This is just a test class for using SET in an HGSETGET subclass.
    properties
        System = '';
    end
    methods
        function H = unit(str)
            if nargin > 0
                H.System = str;
            end
        end
        function varargout = set(H,varargin)
            S = struct('System','[{SI} | cgs]');
            switch nargin
                case 1
                    if nargout < 1
                        disp(S)
                    else
                        varargout{1} = S;
                    end
                case 2
                    if nargout < 1
                        disp(S.System)
                    else
                        varargout{1} = S.System;
                    end
                case 3
                    H.System = varargin{2};
                otherwise
                    error('unit:wrongNumberOfArguments', ...
                        'Wrong number of arguments to SET command.')
            end% switch
        end% set
    end% methods
end% classdef
But I still wonder - is there an implementation that involves a function SET.SYSTEM?
Related Question