The Template Method pattern

The Template Method pattern is a common way to implement an algorithm whose overall structure is pre-determined, but some of the details of the implementation need to be customized. If you are thinking about a solution that goes something like this—first, we do X, then Y, then Z, but how exactly we do Y depends on the data we process—you are thinking about the Template Method. As a pattern that allows the behavior of the program to change dynamically, the Template Method is somewhat similar to the strategy pattern. The key difference is that the strategy changes the entire algorithm at runtime, while the Template Method lets us customize specific parts of the algorithm. This section deals with the latter, while we have a separate Chapter 16, Policy-Based Design, dedicated to the former.

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