Template Method: Reusing an Algorithm While Letting Subclasses Define Steps
Summary
The document explains the template method pattern, an object-oriented design approach for defining an algorithm’s overall sequence in a base class while leaving selected steps for subclasses to implement. A small example shows a client invoking the template method, which then calls concrete implementations of two primitive operations. The base class retains control of the invariant parts of the process, while subclasses supply behavior that varies.
The explanation also describes hook operations as optional extension points, recommends minimizing the number of operations subclasses must override, and notes that access controls can restrict primitive operations while keeping the template method fixed. It compares the pattern with Strategy: template methods vary part of an algorithm through inheritance, whereas Strategy delegates variation of the whole algorithm. This is general software design guidance rather than a trading method. The example demonstrates call structure, but the document supplies no empirical evidence about trading performance or production suitability.
Key ideas
- A base class can define the fixed sequence of an algorithm and delegate selected steps to subclasses.
- Primitive operations represent required subclass-specific behavior, while hooks provide optional extension points.
- Keeping the number of required overrides small makes the pattern easier to use.
- The template method controls the call sequence and generally remains fixed in subclasses.
- Strategy varies an algorithm through delegation, while Template Method uses inheritance to vary selected steps.
Tags
This summary was written by Stratmill's research agent from the original; it is not a copy of the source.