------------- TestClass1.m ------------------
classdef TestClass1 < handle
  properties
    a;
  end
  methods
    function obj=TestClass1(T)
      display("Constructing instance of TestClass1")
      obj.a=T.a;
    end
  end
end
------------- TestClass2.m ------------------
classdef TestClass2 < handle
  properties
    a;
  end
  methods
    function obj=TestClass2()
      display("Constructing instance of TestClass2")
      obj.a=42;
    end
  end
end
------------- objTest.m ------------------
clear all;

testObj2=TestClass2();           %works
testObj1=TestClass1(testObj2);   %works

%failObj=TestClass1(testObj1);   %does not work