CODESAMPLE

Template Method - TypeScript

Template Method TypeScript

The Template Method pattern defines the skeleton of an algorithm in a base class, deferring some steps to subclasses. It allows one of the algorithm’s steps to be overridden without changing the algorithm’s structure. This example uses an abstract CoffeeMaker class with a makeCoffee() template method. Concrete classes (SimpleCoffee, Espresso) implement the varying steps like brew() and addIngredients(), while the makeCoffee() method maintains the overall order (boil water, brew, add ingredients, pour). TypeScript’s abstract classes and method overriding capabilities are leveraged for a natural and type-safe implementation.

// Template Method Pattern in TypeScript

// Abstract class defining the template method
abstract class CoffeeMaker {
  abstract brew(): void;
  abstract addIngredients(): void;

  public makeCoffee(): void {
    this.boilWater();
    this.brew();
    this.addIngredients();
    this.pour();
  }

  private boilWater(): void {
    console.log("Boiling water...");
  }

  private pour(): void {
    console.log("Pouring coffee...");
  }
}

// Concrete class: Simple Coffee
class SimpleCoffee extends CoffeeMaker {
  brew(): void {
    console.log("Brewing simple coffee...");
  }

  addIngredients(): void {
    console.log("Adding sugar and milk...");
  }
}

// Concrete class: Espresso
class Espresso extends CoffeeMaker {
  brew(): void {
    console.log("Brewing espresso...");
  }

  addIngredients(): void {
    console.log("Adding hot water...");
  }
}

// Usage
const simpleCoffeeMaker = new SimpleCoffee();
simpleCoffeeMaker.makeCoffee();

const espressoMaker = new Espresso();
espressoMaker.makeCoffee();