Design Patterns

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Questions and Answers

What is the main motto of Object-Oriented Design (OOD) principles?

Divide and conquer.

Practice makes perfect.

Imitation is the sincerest form of not being stupid. (correct)

Imitation is the sincerest form of flattery.

What is the primary goal of the Single Responsibility Principle (SRP)?

To increase code complexity

To make code more readable and maintainable (correct)

To allow multiple reasons for change

To decrease code extendability

What type of patterns deals with GUI design?

Database Patterns

Concurrency Patterns

Architectural Patterns

GUI Design Patterns (correct)

What is an example of a Concurrency Pattern?

Double buffering Signup and view all the answers

What does ISP stand for in SOLID principles?

Interface Segregation Principle Signup and view all the answers

What is an example of a GRASP pattern?

Low Coupling/High Cohesion Pattern Signup and view all the answers

What is an example of an Anti-pattern?

God Class Signup and view all the answers

How many essential elements are there in a design pattern?

5 Signup and view all the answers

What is the main benefit of following the Don't Repeat Yourself Principle?

It makes the code easier and safer to maintain. Signup and view all the answers

What does the Acyclic Dependencies Principle aim to achieve in software design?

To create a cycle-free dependency graph Signup and view all the answers

Which type of design pattern is focused on the creation of objects?

Creational Signup and view all the answers

Which principle favors polymorphic composition of objects over inheritance?

Composite Reuse Principle Signup and view all the answers

What is the primary purpose of inheritance in object-oriented programming?

To inherit members from a base class. Signup and view all the answers

What is the advantage of decoupling in software design?

It reduces dependencies between components. Signup and view all the answers

What is the primary goal of the GRASP principles in object-oriented design?

To assign responsibility to classes and objects Signup and view all the answers

Which of the following is NOT a GRASP principle?

Single Responsibility Principle Signup and view all the answers

Which principle is related to the idea of not forcing clients to depend on interfaces they don't use?

Interface Segregation Principle Signup and view all the answers

What is the term for a graph with no cycles, as referred to in the Acyclic Dependencies Principle?

Directed Acyclic Graph Signup and view all the answers

What is the term for a design pattern that addresses a fundamental problem in software design?

Fundamental pattern Signup and view all the answers

Which of the following is NOT a type of design pattern based on the problem it addresses?

Architectural Signup and view all the answers

What is the benefit of following the Composite Reuse Principle in software design?

Improved flexibility and maintainability Signup and view all the answers

Which of the following is an example of a class-level design pattern?

Inheritance Signup and view all the answers

Study Notes

Design Patterns

5 essential elements of a pattern: pattern name, problem description, solution, consequences, and implementation
Types of patterns:
- Architectural Patterns (e.g., MVC, Layers)
- GUI Design Patterns (e.g., Window per task, Disabled irrelevant things, Explorable interface)
- Database Patterns (e.g., decoupling patterns, resource patterns, cache patterns)
- Concurrency Patterns (e.g., Double buffering, Lock object, Producer-consumer, Asynchronous processing)
- Enterprise (J2EE) Patterns (e.g., Data Access Object, Data Transfer Object)

Design Principles

OOD key principles: "Imitation is the sincerest form of not being stupid"
Design Goals: code should be readable, extendable, modifiable, testable, and easy to refactor
SOLID design principles:
- SRP (Single Responsibility Principle): a class should have one and only one reason to change
- OCP (Open-Closed Principle)
- LSP (Liskov Substitution Principle)
- ISP (Interface Segregation Principle)
- DIP (Dependency Inversion Principle)

Single Responsibility Principle (SRP)

A class should have one and only one reason to change
Code will be simpler and easier to maintain
Example: Container and Iterator (Container manages objects; Iterator traverses the container)
How to spot multiple responsibilities: forming sentences ending in itself

Don't Repeat Yourself (DRY)

Avoid duplicate code by abstracting out things that are common and placing those things in a single location
No duplicate code => ONE requirement in ONE place
This principle can and should be applied everywhere (e.g., in Analysis phase – don't duplicate requirements or features)

Types of Design Patterns

Based on the type of the problem it addresses (Purpose):
- Fundamental
- Creational
- Structural
- Behavioral
Based on the technique it uses (Scope):
- Class (uses inheritance)
- Object (uses object composition)

Fundamental Patterns

Inheritance: a mechanism that allows a class A to inherit members of a class B
Acyclic dependencies principle: the dependency graph of packages or components should have no cycles
Composite reuse principle: favor polymorphic composition of objects over inheritance

GRASP (General Responsibility Assignment Software Patterns)

Guidelines for assigning responsibility to classes and objects in object-oriented design
Includes patterns and principles such as:
- Controller
- Creator
- Indirection
- Information Expert
- High Cohesion
- Low Coupling
- Polymorphism
- Protected Variations
- Pure Fabrication

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Description

This quiz covers the 5 essential elements of design patterns, including pattern name, problem description, solution, consequences, and implementation. It also explores different types of patterns such as architectural, GUI design, database, and concurrency patterns.