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Which design pattern allows you to add responsibilities to objects at runtime by wrapping them with additional behavior without modifying their code or creating subclasses?

easy💻🤔 Programming Reasoning Q1 of Q15

OOP & Design Patterns - Decorator Pattern - Wrapping Behaviour Without Subclassing

Which design pattern allows you to add responsibilities to objects at runtime by wrapping them with additional behavior without modifying their code or creating subclasses?

ADecorator Pattern

BFactory Pattern

CSingleton Pattern

DObserver Pattern

Step-by-Step Solution

Solution:

Step 1: Understand the requirement
The need is to add behavior dynamically without subclassing or modifying existing code.
Step 2: Identify the pattern
The Decorator Pattern wraps an object to add responsibilities at runtime.
Final Answer:
Option A -> Option A
Quick Check:
Adding behavior dynamically without subclassing? Decorator [OK]

Quick Trick: Dynamic behavior addition without subclassing? Decorator [OK]

Common Mistakes:

MISTAKES

Confusing with Factory which creates objects but doesn't add behavior dynamically.
Singleton controls instance creation, not behavior extension.
Observer is for event notification, not behavior wrapping.

Trap Explanation:

PITFALL

Factory and Singleton patterns are about object creation, not dynamic behavior extension.

Interviewer Note:

CONTEXT

Tests understanding of the core purpose of the Decorator Pattern.

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