One of my biggest beefs with the STL and the C++ primitives, and a complaint I frequently hear being voiced, is that they are not object-oriented. One of the joys of C++ is that it is immensely flexible and powerful, so it does give us the tools to define our own object-oriented libraries.

Up until recently the only real obstacle I faced in making my own object oriented library was that polymorphism was expensive. The problem is now no longer significant with a new C++ interfaces library about to be released as a beta-release by Jonathan Turkanis called the Boost Interfaces Library ( BIL ). The BIL is not yet in fact a Boost library, but the name reflects the intention for eventual submission to the library.

The BIL is a set of macros which use a technique I wrote about in the September 2004 issue of the C++ Users Journal for implementing efficient interfaces without abstract base classes. The major advantages of this technique are that it provides us with run-time polymorphism without the overhead of virtual tables within objects. This means we can uses lightweight objects efficiently. Another advantage is that there is no need to pre-declare the intention of implementing interface as is required in Java and C#.

The OOTL has two primary sub-libraries, one for primitives and the other for collections. The OOTL primitives library, provides lightweight object-oriented alternatives to the C++ built-in types. The OOTL collections library provides a set of interfaces and classes for abstract data types such as Stacks, Queues, Deques, Arrays, Lists and so on.

DoSomethingWithStack(ootl::IStack<Object> stack) 
{ ... }

DoSomethingWithStack(std::stack<Object> stack)
{ ... }

 template<typename Stack_T>
DoSomethingWithStack(Stack_T stack) 
{ ... }

template<typename Elem_T>
class Iter {
  Bool IsAtEnd();
  void GotoFirst();
  void GotoNext();
  Elem_T& Get(); 
}