[solved-ish] How do I convert to base type?

[Duthomhas]

This is one that I've never quite "got".

How do I assign a derived class type to its base class type?

Concretely:

I'm making myself a std::basic_string<>-derived class that overloads all the comparison functions to work case-insensitively. In all other respects it should be identical to a normal string --it stores and writes and reads and quuxes its data with case-sensitivity just like the base class --because it inherits all that behavior.

(Aside: The reason I didn't just play with the std::char_traits<> is because doing so invalidates use of the class with things like cout etc.)


Now I know that the instant answer is: because a derived class is different than a base class --otherwise they would be the same class...

But in this case, I don't care. If I assign a basic_cistring<> to a basic_string<> it will (obviously) loose all its case-insensitive comparison powers. That is correct.

BUT, the problem is I just don't quite understand how to initialize a base reference with the derived reference.

I've tried this:

template <...>
struct base_cistring: public std::basic_string <...>
  {
  ...
  operator std::basic_string <...> ()
    {
    return std::basic_string <...> ( this->c_str(), this->length() );
    }
  ...
  };

which compiles fine, but doesn't seem to get used...

I've also tried overloading the assignment operator:

template <...> inline
std::basic_string <...> operator = ( const basic_cistring <...> & source )
  {
  ...
  }

but the compiler complains to me that this must be a non-static member function (even though the assignment is not to the derived class!).

Alas! I'm over my head with this issue. Help!

:-(

[edit] fixed typo
[edit2] Man, having written that, I think I forgot an argument to the = operator. Let me fix that and I'll post back if it works..
[edit3] Argh. Nope, problem remains.


[final edit]
Well, it seems that you can assign to the base type (I thought you could!), but I also needed to override all the class constructors...

<grumble>

:-)