The Template Method Pattern and the Non-Virtual Idiom
The Template Method is one of the classic Gang of Four design patterns, or, more formally, one of the 24 patterns described in the book Design Patterns – Elements of Reusable Object-Oriented Software by Erich Gamma, Richard Helm, Ralph Johnson, and John Vlissides. It is a behavioral design pattern, meaning that it describes a way for communicating between different objects. As an object-oriented language, C++, of course, fully supports the Template Method pattern, although there are some implementation details that are specific or unique to C++ that this chapter will elucidate.
The following topics will be covered in this chapter:
- What is the Template Method pattern, and what problems does it solve?
- What is the non-virtual interface?
- Should you make virtual functions public, private, or protected by default?
- Should you always make destructors virtual and public in polymorphic classes?
