What Are the Components of Strategy Pattern?

The Strategy design pattern is a behavioral pattern that enables an algorithm's behavior to be selected at runtime. It allows you to define a family of algorithms, put each of them into a separate class, and make their objects interchangeable. This pattern primarily consists of three key components that work together to achieve flexible and interchangeable algorithms.

Core Components of the Strategy Pattern

The Strategy pattern is comprised of the following fundamental components:

• Context
• Strategy Interface
• Concrete Strategies

These components collaborate to decouple the client code from the specific algorithm implementation, promoting flexibility and maintainability.

1. Context

The Context is the class that utilizes the Strategy. It maintains a reference to a Strategy object and delegates the execution of the algorithm to this object. The Context class itself does not know the concrete implementation of the algorithm; it only knows about the Strategy interface. This allows the Context to be configured with different concrete strategies at runtime, enabling it to change its behavior dynamically.

• Responsibility: The Context is responsible for maintaining a reference to a Strategy object.
• Behavior: It provides a method that allows clients to set or change the concrete strategy it uses.
• Interaction: The Context delegates the execution of the algorithm to the associated Strategy object.

2. Strategy Interface

The Strategy Interface (also known as the Strategy or Algorithm interface) declares a common method or set of algorithm execution techniques. This interface serves as a contract for all concrete strategies, ensuring they implement a specific set of methods that the Context can call. It establishes a common API that allows the Context to interact with any concrete strategy without knowing its specific type.

• Declaration: It declares a common method signature for the algorithms.
• Contract: Defines the contract that all concrete strategies must adhere to.
• Decoupling: Decouples the Context from the specific algorithm implementations.

3. Concrete Strategies

Concrete Strategies are classes that implement the Strategy interface. Each Concrete Strategy class provides a specific implementation of the algorithm declared by the Strategy interface. These classes encapsulate different variations of the algorithm, allowing them to be swapped in and out of the Context interchangeably.

• Implementation: Each Concrete Strategy provides a unique implementation for the method(s) defined in the Strategy interface.
• Encapsulation: Encapsulates a specific algorithm or behavior.
• Interchangeability: Multiple Concrete Strategies can exist, each offering a different way to perform the same task, making them interchangeable within the Context.

Summary of Components

By separating the algorithm from the client that uses it, the Strategy pattern promotes loose coupling, enhances reusability, and makes it easier to add new algorithms without modifying existing code.