calling method (and sum'ing answer) on every class instance in a matrix

Hi, I asked a very similar question to this this morning for getting the sum of class properties in a matrix (cheers Daniel for the answer) but now I need to get the sum of method return values.

If I make a simple class;

MATLAB code
classdef ExampleClass < handle
 methods
   function obj = GetTotal(this)
      %In real life this is a calculation that returns a value.
      obj = 5;
   end
 end
end

And I make a collection of them;

MATLAB code
myCollection=[ExampleClass1; ExampleClass2; ExampleClass3; ExampleClass4];

Is there an easy way to get the sum of the GetTotal methods please? ie,

MATLAB code
sum([myCollection.GetTotal])

...would give 20?

Is it possible without making the method a dependent property?

Thanks for any help,

Tom.

Answer 1

[David Young]

sum(arrayfun(@(x) GetTotal(x), myCollection))

Answer 2

[Daniel Shub]

Welcome to the joys of MATLAB OOP. While TMW will tell you that the array nature of the OOP system is a real plus, I find it a real pain to work with. Your options are to either limit your class to scalars (i.e., not allowing myCollection) or to write your own subsref. Something like:

function varargout = subsref(obj, S)
  for ii = 1:numel(obj)
    varargout{ii} = builtin('subsref', obj(ii), S);
  end
end

is a reasonable starting point, but it quickly gets more complicated.