Type Erasure in C++: The Glue between Object-Oriented and

C++ is a multi-paradigm language. The two main paradigms in C++ are object-oriented programming and generic programming. Many real-world C++ software projects use these two paradigms side by side. This creates considerable tension due to the fact that object-oriented programming is largely based on the judicious choice of types and hierarchies, while generic programming tends to cause an abundance of unrelated types. We show how type erasure can reconcile these conflicting tendencies. We present iterator type erasure as a concrete example that we have implemented and that is being used in production code at Zephyr Associates, Inc.. The Tension between Object-Oriented and Generic Programming The most widely used programming paradigms in C++ are object-oriented program-ming (classes, objects, and runtime polymorphism come to mind) and generic pro-gramming (algorithms, templates, and compile time polymorphism come to mind). A cornerstone of object-oriented programming is the judicious choice of types and hierarchies. Much of what has been written on object-oriented programming is centered around “object-oriented analysis and design. ” The gist of this approach is that the classes—that is, the types—in an object-oriented piece of software shoul