johnnystefan/pattern-prototype

Skill: Implement Prototype Pattern

Purpose

Enables copying existing objects without making the code dependent on their classes. The cloning responsibility is delegated to the objects themselves.

Procedural Instructions

1. Create Prototype Interface: Define a clone() method.
2. Implement Clone in Classes: The class must instantiate itself and copy all field values (including private ones) to the new instance.
3. Prototype Registry (Optional): A central place to store frequently used prototypes for easy cloning.

TypeScript Example

abstract class Shape {
  constructor(
    public x: number,
    public y: number,
    public color: string,
  ) {}
  abstract clone(): Shape;
}

class Rectangle extends Shape {
  constructor(source: Rectangle) {
    super(source.x, source.y, source.color);
    this.width = source.width;
  }
  public width: number = 0;
  clone(): Shape {
    return new Rectangle(this);
  }
}

Payoff

• Efficiency: Cloning is often cheaper than full initialization.
• Abstraction: You can clone objects without knowing their specific types.