OOP subsref runs twice with "end"?

I have a simple object:

classdef objTest
  methods
      function [varargout]=subsref(obj,S)
          disp(S)
          varargout={[]}; %irrelevant for this test...
      end
  end
end

Now if I do o = objTest; o.test{1}(1:end), it displays S twice, first showing only the . and {} references, and then again showing all 3. Can anyone explain why this happens? I assume it's somehow related to a builtin function running to figure out how to evaluate the "end"?

Answer 1

[Matt J]

I assume it's somehow related to a builtin function running to figure out how to evaluate the "end"?

Yes. The expression o.test{1}(1:end) is equivalent to

      temp=o.test{1};
      n=numel(temp);
      o.test{1}(1:n);

So, subsref is called twice. If you had done o.test{end}(1:end), then it would have been called three times.