Object-Oriented Principles

Question 1

SOLID Principles?

Answer 1

Single-Responsibility Principle
Open Closed Principle
Liskov Substitution Principle
Interface Segregation Principle
Dependency Inversion Principle

Question 2

Single-Responsibility Principle?

Answer 2

A class should have one, and only one reason to change

SoC principle that focuses on managing change by assigning cohesive responsibilities.

Question 3

Open-Closed Principle

Answer 3

You should be able to extend the behaviour of a module without modifying it

A module is closed for modification but open to be extended.

Question 4

How is Open-Closed Principle achieved?

Answer 4

Loose coupling
Abstraction
Polymorphism

Question 5

Liskov Substitution Principle?

Answer 5

Subclasses should be substitutable for their base classes

Dictates the correct implementation of the IS-A relationship

Question 6

Interface Segregation Principle?

Answer 6

Many client specific interfaces are better than one general purpose interface

Critical principle to follow in the design of interfaces who are much more focused than the classes that implement them

Question 7

Dependency Inversion Principle?

Answer 7

Depend upon Abstractions. Do not depend upon concretions

Definition of use of abstraction to ensure loose coupling.
Enables dependency injections and associated frameworks

Question 8

S
O
L
I
D

Answer 8

High Cohesiveness
Code Reuse
Code Reuse
SoC
Loose Coupling

Question 9

4 Essential elements in Design Pattern?

Answer 9

Pattern Name
Problem
Solution
Consequencies

Question 10

What did GoF do?

Answer 10

GoF established a paradigm for cataloguing and reuse of design solutions

Question 11

Pattern Catagorization?

Answer 11

Architecture Patterns
Design Patterns
Idioms

Question 12

Architectural Patterns?

Answer 12

Expresses fundamental structural organizartion of software systems; predefined subsystems and their responsibilities and relationships
* Large Scale Patterns

Question 13

Design Patterns?

Answer 13

Medium Scale Patterns

Question 14

Idioms?

Answer 14

Programming language specific pattern that describes how to implement particular aspects of components, relationships or functionality

Question 15

Pattern Classification By Purpose list

Answer 15

Creational Patterns
Structural Patterns
Behavioural Patterns

Question 16

Creational Patterns?

Answer 16

Address the instantiation process as a separate concern
Make system independent
Emphasize object composition vs class inheritance to decrease coupling

Question 17

Structural Patterns?

Answer 17

Ways to compose classes and objects to from larger structure to realize new functionality that can be easily extended

Question 18

Behavioural Patterns?

Answer 18

Representing algorithms and assignment of responsibilities between objects and focus on patterns of communication between objects

Question 19

Pattern Classification by Scope?

Answer 19

Class Patterns

Object Patterns

Question 20

Class Patterns?

Answer 20

Focus on relationships between classes and subclasses.
Inheritance relationships are defined at compile-time
Focus on code reuse

Question 21

Object Patterns?

Answer 21

Focus relationships between objects, specifically composition and aggregation.
Relationships are dynamic
Focus on code reuse through flexibility

Question 22

Roles in Abstract Factory Pattern?

Answer 22

Abstract Factory
Concrete Factory
Abstract Product
Concrete Product

Question 23

Consequencies of Abstract Factory?

Answer 23

Isolates the client from specific concrete classes making clients dependent only on interfaces

Question 24

Roles in Factory Method Pattern?

Answer 24

Creator
ConcreteCreator
Product
ConcreteProduct

Question 25

What is Creator?

Answer 25

Declares the factory method which returns an abstract product or product interface

Question 26

ConcreteCreator?

Answer 26

Implement the factory method by creating a concrete product that is used by the creator or by one of its client

Question 27

Product?

Answer 27

Defines the interface of the products that are being created by the factory method

Question 28

ConcreteProduct?

Answer 28

Implement the product interface this representing a concrete product that will be used

Question 29

Singleton?

Answer 29

The singleton ensure that only one isntance of given class is being created and used in a system

Question 30

Consequences of Singleton?

Answer 30

Provides encapsulation and controller access to global variables
More flexible than using static classes which cannot be extended and are not polymorphic

Question 31

Caveats of Singleton?

Answer 31

Multiple singletons may have interdependencies that may be difficult to manage as the order of creation depends on the usage order

Question 32

Composite?

Answer 32

Composite objects into tree structures letting clients treat individual objects and compositions of objects uniformly

Question 33

Roles in the Composite Pattern?

Answer 33

Component
Leaf
Composite

Question 34

What is Decorator?

Answer 34

Attach additional responsibilities to an object dynamically