MATLAB: How to use the SUBSREF function to behave as the BUILTIN only for a subset of subscripted references in MATLAB 7.8(R2009a)

MATLABoopsubsref

I would like to create a SUBSREF function for my class. I am coding the SUBSREF method to behave like a custom SUBSREF for a subset of the subscription symbols and behave like the builtin SUBSREF for the rest. This presents a challenge, as the private and protected properties and methods are accessible inside the custom SUBSREF function. What steps can I take to make sure my private and protected properties and methods are not visible?
Reproduction Steps:
classdef testclass
      properties (Access = protected)
          prop1 = 1;
          prop2 = 2;
      end
      % constructor
      methods (Access = public)
          function TC = testclass()
          end
      end
      % Overloaded subsref
      methods
          function vals = subsref(TC,s)
              switch s(1).type
                  case '.'
                      vals = builtin('subsref',TC,s);
                  case '()'
              end
          end
      end
      methods (Access = protected)
          function showvals(TC)
              disp('prop1 =');
              disp(TC.prop1);
              disp('prop2 =');
              disp(TC.prop2);
          end
      end
end
t = testclass
t.prop1

Best Answer

This can be acheived by checking for the access information for the Properties and having an if - else statement so that SUBSREF behaves as intended.
An example of the check that you can perform is as follows:
if any(strcmp(s(1).subs,properties(TC))) || any(strcmp(s(1).subs,methods(TC)))
vals = builtin('subsref',TC,s);  
else
error(['''%s'' is not a public property or method of the ''testclass'' class.'],s(1).subs);
end
Another way to get information about the properties of the class is to use meta.class option.
mc = metaclass(TC);
p = [mc.Properties{:}];
   names = {p.Name};
p(strcmp('prop1, names)).GetAccess
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