Template Method

Intent, Motivation, Applicability, Structure, Participants, Collaborations, Consequences, Implementation, Sample Code, Known Uses, Related Patterns

Implementation

Three implementation issues are worth noting:

1. Using C++ access control. In C++, the primitive operations that a template method calls can be declared protected members. This ensures that they are only called by the template method. Primitive operations that must be overridden are declared pure virtual. The template method itself should not be overridden; therefore you can make the template method a nonvirtual member function.
2. Minimizing primitive operations. An important goal in designing template methods is to minimize the number of primitive operations that a subclass must override to flesh out the algorithm. The more operations that need overriding, the more tedious things get for clients.
3. Naming conventions. You can identify the operations that should be overridden by adding a prefix to their names. For example, the MacApp framework for Macintosh applications prefixes template method names with ``Do-'': ``DoCreateDocument'', ``DoRead'', and so forth.

Implementation of Abstract Factory, Adapter, Bridge, Builder, Chain of Responsibility, Command, Composite, Decorator, Facade, Factory Method, Flyweight, Interpreter, Iterator, Mediator, Memento, Observer, Prototype, Proxy, Singleton, State, Strategy, Template Method, Visitor