johnnystefan/pattern-strategy

Skill: Implement Strategy Pattern

Purpose

Defines a family of algorithms, encapsulates each one, and makes them interchangeable. Strategy lets the algorithm vary independently from clients that use it.

Procedural Instructions

1. Identify Variant Algorithms: Look for a class that performs a task in multiple different ways.
2. Declare Strategy Interface: Define a common method for executing the algorithm.
3. Implement Concrete Strategies: Place each variation of the algorithm into its own class.
4. Update Context: The original class stores a reference to a Strategy and delegates work to it.
5. Set Strategy at Runtime: Provide a setter in the Context so the client can swap strategies.

TypeScript Example

interface RouteStrategy {
  buildRoute(a: string, b: string): void;
}

class WalkingStrategy implements RouteStrategy {
  buildRoute(a: string, b: string) {
    console.log('Walking route...');
  }
}

class Navigator {
  // Context
  private strategy!: RouteStrategy;
  setStrategy(s: RouteStrategy) {
    this.strategy = s;
  }
  calculate(a: string, b: string) {
    this.strategy.buildRoute(a, b);
  }
}

Payoff

• Flexibility: Switch algorithms used inside an object at runtime.
• Isolation: Separates the implementation details of an algorithm from the code that uses it.