aa.cpp

aa.cpp

class A {
private:
  A() {};
public:
  static A factory_A() { reutrn A(); }
}

// friend declaration for std::make_shared
// works on VS2010
friend std::tr1::_Ref_count_obj<T>
// works on VS2015
friend std::_Ref_count_obj<PngImage>;


class A {
private:
  A() {};
  class PrivateKey() {};
public:
  A(PrivateKey) : A() {}
  static std::shared_ptr<A> factory_A() { reutrn make_shared<A>(PrivateKey()); }
}