Thread Subject: 2008a OOP problem

I have a very basic question about inheriting from built-in
classes in matlab 2008a. The following class inherits from
double:

classdef graph < double
   methods
       function obj = graph(g)
          % constructor
          
           obj = obj@double(g);
       end
       
       function v = val(g,x)
           v = g(x);
       end
       
   end
end

suppose I now call:

g = graph([0 1 0;1 0 1;0 1 0]);

g(1) will give me the answer: 0

whereas val(g,1) will give me the whole matrix

for some reason the indexing functions of double are not
properly called in the class method. Also, if I define
subsref for this derived class then it will not get called
by the function val(g,x). Am I missing something or is this
a serious bug???

Cheers,

Marcel

Hello Mercel,

In MATLAB, overloaded subsref and subsasgn are not called from inside
methods of a class. You can implement val(g,x) as follows:
  function v = val(g, x)
    d = double(g);
    v = d(x); % or v = graph(d(x)) if you want to return a graph
  end

-Dave

"Marcel " <marcel.van.gerven@gmail.com> wrote in message
news:fvrmi6$f2p$1@fred.mathworks.com...
>I have a very basic question about inheriting from built-in
> classes in matlab 2008a. The following class inherits from
> double:
>
> function v = val(g,x)
> v = g(x);
> end
> suppose I now call:
> g = graph([0 1 0;1 0 1;0 1 0]);
> g(1) will give me the answer: 0
> whereas val(g,1) will give me the whole matrix