Strategy design pattern

The strategy design pattern is a behavioral software design pattern that allows you to select an algorithm at runtime. Instead of implementing a single algorithm directly, code receives run-time instructions as to which in a family of algorithms to use. This allows you to easily change the algorithm used by a piece of code without having to change the code itself.

Key points of the Strategy Design Pattern:

• Intent:

  • The main intent of the Strategy pattern is to define a family of algorithms, encapsulate each one, and make them interchangeable. It enables the client to choose the appropriate algorithm at runtime.

• Key Components:

  • Context:
    • Maintains a reference to the strategy object and may define an interface that allows the strategy to be set at runtime.
  • Strategy:
    • Declares an interface for a family of algorithms. Concrete strategies implement this interface.
  • ConcreteStrategy:
    • Implements the algorithm defined by the Strategy interface. There can be multiple concrete strategies that the context can use interchangeably.

• Encapsulation:

  • Each algorithm is encapsulated into a separate class, known as a strategy.
  • Strategies are interchangeable, meaning they can be easily swapped without affecting the client code.

• Abstraction:

  • The pattern uses abstraction to provide a common interface for all strategies, ensuring they follow the same contract.

• Flexibility:

  • It promotes flexibility by allowing clients to choose the most suitable strategy at runtime.
  • New strategies can be added without modifying existing code.

• Separation of Concerns:

  • It helps in separating the algorithmic logic from the client code, promoting a clean and modular design.

• Open/Closed Principle:

  • The pattern follows the Open/Closed Principle, as new strategies can be added without altering the existing code.

• Context:

  • The class that utilizes the strategy pattern is called the context.
  • The context maintains a reference to the strategy interface and can switch between different strategies.

• Advantages:

  • Flexibility and Extensibility: Strategies can be added, removed, or replaced without affecting the client code.
  • Encapsulation: Each strategy is encapsulated, promoting clean code and separation of concerns.
  • Easier Testing: Strategies can be tested independently, making it easier to ensure their correctness.

• Use Cases:

  • The Strategy pattern is useful when there are multiple algorithms for performing a task, and the client needs to select or switch between them dynamically.
  • It is applicable when a class has a behavior that may change frequently or when a class has multiple variants of a behavior.