Interview Q&A

Short answer: PIs (DrawingAPI1 and DrawingAPI2). The client code can easily switch between different rendering styles without changing the shape itself. PIs (DrawingAPI1 and DrawingAPI2). The client code can easily switch between different rendering styles without changing the shape itself. class Program { static void Main() { Shape circle1 = new Circle(5, 10, 2, new…… DrawingAPI1()); Shape circle2 = new Circle(5, 10, 2, new…

Explain a bit more

DrawingAPI2()); circle1.Draw(); // Outputs: Drawing Circle at (5, 10) with radius 2 using API 1.

Real-world example (ShopNest)

Use a GoF pattern in ShopNest only when it removes duplication or makes a change safer—explain the problem it solves in the interview.

Say this in the interview

1. Define — one clear sentence (the short answer above).
2. Example — relate it to a project like ShopNest or your real work.
3. Trade-off — when you would not use it.

Short answer: The ProductCollection class is a concrete aggregate that implements the IAggregate<Product> interface. It maintains a list of Product objects and provides an Add() method to add products. It also implements CreateIterator() to return an instance of ProductIterator, enabling iteration over the collection. public class ProductCollection : IAggregate<Product>

Example code

{
private readonly List<Product> _products = new List<Product>();
public void Add(Product product) => _products.Add(product);
public int Count => _products.Count;
public Product this[int index] => _products[index];
public IIterator<Product> CreateIterator() => new ProductIterator(this); }

Real-world example (ShopNest)

Use a GoF pattern in ShopNest only when it removes duplication or makes a change safer—explain the problem it solves in the interview.

Say this in the interview

1. Define — one clear sentence (the short answer above).
2. Example — relate it to a project like ShopNest or your real work.
3. Trade-off — when you would not use it.

Short answer: The client code uses the factory to create a logger without needing to know which type of logger is being instantiated. Based on the factory used (FileLoggerFactory or ConsoleLoggerFactory), the corresponding logger is created. class Program { static void Main() {

Example code

LoggerFactory factory = new ConsoleLoggerFactory();
ILogger logger = factory.CreateLogger(); logger.Log("This is a log message."); }
}

Real-world example (ShopNest)

Use a GoF pattern in ShopNest only when it removes duplication or makes a change safer—explain the problem it solves in the interview.

Say this in the interview

1. Define — one clear sentence (the short answer above).
2. Example — relate it to a project like ShopNest or your real work.
3. Trade-off — when you would not use it.

Short answer: The Application class accepts an IUIFactory in its constructor. This means the client code can choose which concrete factory (Windows or Mac) to use without changing the Application class itself. public class Application

Example code

{
private readonly IButton _button;
private readonly ICheckbox _checkbox;
public Application(IUIFactory factory)
{
_button = factory.CreateButton();
_checkbox = factory.CreateCheckbox();
}
public void Render()
{ _button.Render(); _checkbox.Render(); }
}

Real-world example (ShopNest)

Use a GoF pattern in ShopNest only when it removes duplication or makes a change safer—explain the problem it solves in the interview.

Say this in the interview

1. Define — one clear sentence (the short answer above).
2. Example — relate it to a project like ShopNest or your real work.
3. Trade-off — when you would not use it.

Short answer: ctual construction steps can differ based on the type of pizza (e.g., Margherita vs. Pepperoni). Key Benefits of the Builder Pattern:

Say this in the interview

1. Define — one clear sentence (the short answer above).
2. Example — relate it to a project like ShopNest or your real work.
3. Trade-off — when you would not use it.

Short answer: PIs (e.g., DrawingAPI3, DrawingAPI4) without needing to modify the existing code. Each concrete drawing API (DrawingAPI1, DrawingAPI2) provides its own implementation of the DrawCircle method, enabling the flexibility to draw in different styles or using different libraries. Key Benefits of the Bridge Pattern:

Say this in the interview

1. Define — one clear sentence (the short answer above).
2. Example — relate it to a project like ShopNest or your real work.
3. Trade-off — when you would not use it.

Short answer: pplication app = new Application(factory); pp.Render(); } } pplication app = new Application(factory); pp.Render(); } } pplication app = new Application(factory); pp.Render(); } } pplication app = new Application(factory); pp.Render(); } }

Real-world example (ShopNest)

ShopNest’s NotificationFactory creates Email or SMS senders based on user preference.

Say this in the interview

1. Define — one clear sentence (the short answer above).
2. Example — relate it to a project like ShopNest or your real work.
3. Trade-off — when you would not use it.

Short answer: Product 1 Product 2 Product 3 How It Works:

Real-world example (ShopNest)

Use a GoF pattern in ShopNest only when it removes duplication or makes a change safer—explain the problem it solves in the interview.

Say this in the interview

1. Define — one clear sentence (the short answer above).
2. Example — relate it to a project like ShopNest or your real work.
3. Trade-off — when you would not use it.