Decorator pattern in LLD - Practice Problems & Coding Challenges

Challenge - 5 Problems

🧠 Conceptual

intermediate

Purpose of the Decorator Pattern

Which of the following best describes the main purpose of the Decorator pattern in system design?

A To add responsibilities to objects dynamically without changing their interface

B To create a fixed set of subclasses for different behaviors

C To replace inheritance with composition for all cases

D To enforce a single instance of a class throughout the system

💡 Hint

Think about how you can add features to an object without altering its core code.

The Decorator pattern allows adding new behavior to objects dynamically by wrapping them, without modifying their interface or using inheritance.

❓ Architecture

intermediate

Component Structure in Decorator Pattern

In the Decorator pattern, which component is responsible for defining the interface that both the core object and decorators implement?

A Concrete Component

B Decorator

C Component Interface

D Client

💡 Hint

This component ensures that decorators and core objects can be used interchangeably.

The Component Interface defines the common interface for both the core object and decorators, allowing decorators to wrap the core object transparently.

❓ scaling

advanced

Scaling Decorators in a High-Traffic System

When applying multiple decorators to enhance an object in a high-traffic system, what is a key consideration to maintain scalability?

A Avoid using decorators and duplicate code instead

B Use inheritance instead of decorators for better performance

C Apply decorators only at compile time to avoid runtime costs

D Minimize the number of decorator layers to reduce overhead

💡 Hint

Think about how wrapping many layers can affect system speed.

Each decorator adds a layer of wrapping which can increase processing time; minimizing layers helps keep the system responsive under load.

❓ tradeoff

advanced

Tradeoff of Using Decorator Pattern

What is a common tradeoff when using the Decorator pattern extensively in a system?

A Loss of object-oriented principles by avoiding inheritance

B Increased complexity in debugging due to many small wrapper objects

C Reduced flexibility because decorators cannot be combined

D Decreased code reuse because decorators duplicate functionality

💡 Hint

Consider how many layers of wrapping affect understanding the flow.

Using many decorators can make the system harder to debug and understand because behavior is spread across multiple small objects.

❓ component

expert

Request Flow in Decorator Pattern

Given a core object wrapped by two decorators, which sequence correctly describes the flow of a method call from the client?

A Client calls outer decorator → outer decorator calls inner decorator → inner decorator calls core object

B Client calls inner decorator → inner decorator calls outer decorator → outer decorator calls core object

C Client calls core object → core object calls inner decorator → inner decorator calls outer decorator

D Client calls outer decorator → core object → inner decorator

💡 Hint

Think about how wrappers delegate calls inward.

The client interacts with the outermost decorator, which delegates the call to the next inner decorator, and finally to the core object.