text: Q:
  
  Indexing operator of an object owned by unique_ptr
  
  I am working on a c++ project. I need to put into a std::vector different classes. I found (Objects of different classes in a single vector?) that it is possible to do this by creating classes with a common type and then putting pointers to the vector. In this case I could cast the pointers to the type I need. This is clear to me.
  It is also mentioned that in principle it is possible to use not just pointers but smart_pointers, i.e std::vector<std::unique_ptr<TMyClass>>. And this is where my problems start. TMyClass has the indexing operator (operator[]).
  Lets say I have std::vector<std::unique_ptr<TMyClass>> A. I try to access an element of the TMyClass object like this A[0][0] or A[0].get()[0] or (A[0])[0] but when I compile I get an error:
  [bcc64 Error] type 'value_type' (aka 'std::unique_ptr<.....>') does not provide a subscript operator
  How can I tell the compiler that the second index is related to TMyClass object and not to the unique_ptr? I would highly appreciate if somebody explains me how to access elements in this case.
  
  A:
  
  You need to extract pointer first 
  A[0]  //type: std::unique_ptr<TMyClass>&
  
  Then extract object from that pointer (pointee)
  *A[0] //type: TMyClass&
  
  And then you can use your overloaded operators on this object
  (*A[0])[0] 
  
  