CPP Design Patterns & Software Architecture

Question 1

What is the Singleton design pattern?

Accepted Answer

A pattern ensuring a class has only one instance and provides a global access point to it

Answer

The Singleton pattern restricts instantiation to one object and provides a static method to access that single instance.

Question 2

What is the Factory Method design pattern?

Accepted Answer

A pattern defining an interface for creating an object but letting subclasses decide which class to instantiate

Answer

The Factory Method pattern delegates object creation to subclasses, allowing a class to defer instantiation of the exact type it will use.

Question 3

What is the Observer design pattern?

Accepted Answer

A pattern defining a one-to-many dependency so that when one object changes state, all its dependents are notified automatically

Answer

The Observer pattern implements publish-subscribe, where a subject maintains a list of observers and notifies them of state changes.

Question 4

What is the Decorator design pattern?

Accepted Answer

Attaching additional responsibilities to an object dynamically without modifying its class

Answer

The Decorator pattern wraps an object to extend its behavior at runtime, providing a flexible alternative to subclassing.

Question 5

What is layered (n-tier) architecture?

Accepted Answer

Organizing code into horizontal layers (presentation, business logic, data) where each layer only communicates with adjacent layers

Answer

Layered architecture separates concerns into stacked layers, promoting maintainability and testability by isolating responsibilities.

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