Fundamental Concepts of Object Oriented Programming

Summary

This script introduces the core principles of object-oriented programming (OOP): abstraction, encapsulation, inheritance, and polymorphism. It explains how abstraction simplifies real-world complexity for software applications, encapsulation hides object complexities, and inheritance allows classes to derive properties and methods from others, creating a hierarchy. Polymorphism enables subclasses to implement inherited methods uniquely, showcasing OOP's power in creating flexible, reusable code.

Takeaways

• 🧩 **Abstraction**: Simplifies reality by focusing only on the data and processes relevant to the application being built.
• 📦 **Encapsulation**: Binds data and the programs that manipulate it together, hiding their complexity from the outside.
• 🔄 **Inheritance**: Allows a class to derive its methods and properties from another class, creating a hierarchy of superclasses and subclasses.
• 🌟 **Polymorphism**: Enables a class to implement an inherited method in its own way, allowing different subclasses to behave differently despite sharing the same interface.
• 🚗 **Objects in OOP**: Represent real-world entities or concepts that the software application is interested in, both physical and abstract.
• 📘 **Classes as Templates**: Serve as blueprints for creating objects, defining their attributes and operations (methods).
• 🔑 **Properties and Methods**: Properties describe an object's data, while methods are the actions that can be performed on or by the object.
• 🌐 **Instantiation**: The process of creating an object from a class, making each object a unique instance with its own state.
• 🔗 **Constructors**: Special methods used during instantiation to assign initial values to an object's properties.
• 🛡️ **Information Hiding**: A principle of encapsulation that protects the internal state of an object from external interference and misuse.
• 🔀 **Type Relationships**: Inheritance defines 'is-a' relationships, where subclasses are specific types of their base classes.

Q & A

What are the four fundamental concepts of object-oriented programming?

The four fundamental concepts of object-oriented programming are abstraction, encapsulation, inheritance, and polymorphism.

What is an object in the context of object-oriented programming?

An object in object-oriented programming is anything of interest to the software application being built, which can be a physical thing like a car or a non-physical entity like a bank account.

What is abstraction in object-oriented programming?

Abstraction in object-oriented programming is the process of simplifying reality to focus only on the data and processes that are relevant to the application being built.

What is a class and how does it relate to objects?

A class is a template for creating objects, defining the attributes (properties) and operations (methods) of an object. It is used to instantiate objects, which are instances of the class.

What is encapsulation and why is it important?

Encapsulation is the concept of hiding the complexity of an object's inner workings from the outside. It is important for information hiding and ensuring the integrity and safety of the data and operations within the object.

How does inheritance work in object-oriented programming?

Inheritance allows a class to derive its methods and properties from another class, creating a hierarchy of classes where a subclass inherits features from its superclass.

What is polymorphism and how does it relate to object-oriented programming?

Polymorphism allows a class to implement an inherited method in its own way, enabling different subclasses of the same superclass to behave differently despite sharing the same interface.

What is a constructor in the context of object-oriented programming?

A constructor is a special method used during the instantiation of an object, allowing the assignment of values to properties at the time of object creation.

How does the concept of a 'state' of an object relate to its properties?

The 'state' of an object refers to the values assigned to its properties, making each object of the same type a unique entity.

What is the difference between a base class and a subclass in terms of inheritance?

A base class is the class at the start of the inheritance hierarchy, while a subclass is any class that derives from another class, inheriting its methods and properties.

Why is it beneficial for a programmer to use a class library?

Using a class library is beneficial because it simplifies the use of objects and ensures that the data and operations encapsulated within are safe, without needing to understand the inner workings of the class.

Outlines

00:00

📚 Introduction to Object-Oriented Programming Concepts

The paragraph introduces the core concepts of object-oriented programming (OOP): abstraction, encapsulation, inheritance, and polymorphism. It begins by defining an object as a real-world entity or an abstract concept that a software application interacts with. The paragraph explains abstraction as the process of simplifying complex realities to focus on relevant data and tasks. A class is described as a blueprint for creating objects, detailing its attributes (or properties) and operations (or methods). The paragraph also touches on instantiation, where objects are created from classes, and the role of constructors in setting initial property values. Encapsulation is introduced as a means to hide the internal workings of an object, ensuring data integrity and protecting it from external interference.

05:01

🔗 Inheritance and Polymorphism in OOP

This paragraph delves into the concepts of inheritance and polymorphism within OOP. Inheritance allows a class to derive methods and properties from another class, creating a hierarchy of classes. It uses the example of a 'Person' class and how 'Employee' and 'Customer' classes can inherit from it, potentially extending it with additional properties and methods. The paragraph also discusses the notion of a base class, subclasses, and superclasses in the context of inheritance. Polymorphism is explained as the ability of subclasses to implement inherited methods in their own unique ways, allowing different behaviors while maintaining the same interface. The paragraph concludes by summarizing the four fundamental concepts of OOP, emphasizing how they contribute to building robust and maintainable software applications.

Keywords

💡Object

In the context of the video, 'Object' refers to a fundamental concept in object-oriented programming (OOP). It represents a thing from the real world or a concept that can be modeled in a software application. Objects can be physical, like a car or a book, or abstract, like a bank account or a reservation. The video emphasizes that objects in OOP are simplified models that encapsulate relevant data and behaviors. For example, a 'Person' object might include properties like name and age and methods like 'speak' or 'eat'.

💡Abstraction

Abstraction is one of the four fundamental concepts of OOP discussed in the video. It involves simplifying complex reality to focus on the relevant aspects for the application being developed. The video explains that when creating an object, programmers are only concerned with the data and tasks that are pertinent to the application, rather than every detail of the object. For instance, a 'Car' object might only include properties like 'color' and 'speed', abstracting away the complex mechanical details.

💡Class

A 'Class' is described in the video as a blueprint or template for creating objects. It defines the structure of the objects, including their attributes (properties) and behaviors (methods). The video uses the analogy of a pastry cutter to illustrate how a class can be used to create multiple instances (objects) of the same type. Classes are crucial for encapsulating the properties and methods that are common to all objects of that type.

💡Encapsulation

Encapsulation is another core concept of OOP highlighted in the video. It refers to the bundling of data with the methods that operate on that data, and the restriction of direct access to some of an object's components. This concept is also known as information hiding. The video explains that encapsulation protects the integrity of the data and the methods by keeping the internal workings of an object hidden from the outside, which simplifies the interface for other programmers and prevents unauthorized access.

💡Inheritance

Inheritance is a key concept in OOP that allows a class to derive or inherit properties and methods from another class. The video uses the example of an 'Employee' class inheriting from a 'Person' class, which means the 'Employee' class automatically has the attributes and behaviors of a 'Person', and can also have additional properties specific to employees. Inheritance promotes code reusability and establishes a hierarchical relationship between classes.

💡Polymorphism

Polymorphism is the ability of different classes to implement the same method in different ways. The video explains that polymorphism allows a subclass to override an inherited method with its own specific implementation. This is exemplified by a 'Customer' class that might override a 'saveDetails' method inherited from a 'Person' class to save details to a different database. Polymorphism enables objects of different classes to be treated as objects of a common superclass, while still behaving in their own unique ways.

💡Instantiation

Instantiation is the process of creating an object from a class. The video mentions that once a class is defined, it can be used to instantiate multiple objects, each of which is an instance of that class. Instantiation is a key process in OOP as it brings the abstract class definition into a concrete object with its own state and behavior.

💡Properties

Properties are attributes of an object that describe its state. The video explains that properties are defined within a class and can be assigned values either through property procedures or during instantiation via a constructor. Properties are a way to store data within an object, and they are integral to the object's state, which is the collection of all property values.

💡Methods

Methods are the operations or behaviors that can be performed by an object. As described in the video, methods are programs within a class that define the actions an object can take. They are a way to encapsulate the behaviors of an object, making it easier to manage and use the object in a program. Methods can be procedures or functions that operate on the object's properties.

💡Constructor

A constructor is a special method used to initialize the properties of an object when it is instantiated. The video explains that constructors can assign initial values to an object's properties, ensuring that each object starts with a valid and consistent state. The constructor is an essential part of the instantiation process, allowing for the creation of fully formed objects.

💡Interface

The term 'interface' in the video refers to the public methods and properties of a class that are accessible to other classes. It defines how a class can be interacted with, without exposing the internal implementation details. The video emphasizes that understanding a class's interface is sufficient for using its objects, which simplifies programming and maintains encapsulation.

Highlights

The four fundamental concepts of object-oriented programming are abstraction, encapsulation, inheritance, and polymorphism.

An object can represent anything of interest to a software application, including both physical and non-physical entities.

Abstraction simplifies reality by focusing on relevant data and tasks for the application being built.

A class is a template for creating objects, defining their attributes and operations.

Attributes describe the object's properties, while operations are the actions that can be performed by the object.

Objects are instances of classes, created through a process called instantiation.

Encapsulation hides the complexity of an object's inner workings, protecting data integrity.

A constructor is a special method used to assign initial values to an object's properties during instantiation.

Inheritance allows a class to derive methods and properties from another class, creating a hierarchy of classes.

A base class is at the start of the inheritance hierarchy, while subclasses derive from it.

Polymorphism enables a class to implement an inherited method in its own way, allowing different behaviors for different subclasses.

The concept of polymorphism allows for the same interface to be implemented differently across subclasses.

Encapsulation ensures that the data and operations within an object are safe from outside interference.

Inheritance can be extended to create more specific types, such as an employee or customer class inheriting from a person class.

A class library is a collection of classes that can be used by other software developers, protecting intellectual property.

The interface of a class is all that is needed for a programmer to use its objects, hiding the implementation details.

Polymorphism literally means 'many forms', allowing objects of the same type to behave differently.

Object-oriented programming concepts enable the creation of flexible and reusable software components.

Transcripts

the four fundamental concepts

of object-oriented programming are

abstraction encapsulation inheritance

and polymorphism before considering what

they mean

first consider what is an object

an object is a thing from the real world

it could be a car a boat or a book

but it might not be something physical

that you can touch

it could be a dental appointment a seat

reservation for the cinema

or a bank account in the realm of object

object-oriented programming

an object is anything of interest to the

software application that you're

building

it's anything that you want to store and

process

data about another name for an object

is an entity

this leads us to the first fundamental

concept

of object-oriented programming namely

abstraction abstraction means to

simplify reality

for example a person is an object

but if you were designing a new

application to process data

about a person it's unlikely that you'd

be interested

in everything there is to know about a

person

rather you would only concern yourself

with the data

that are relevant and the tasks that you

want to perform with those data

to create objects programmatically you

need

a class a class is a template for

creating objects

a class is code written by a programmer

to define the attributes

and the operations of an object

attributes describe the object

they're sometimes referred to as fields

because they contain data

most programmers know them as properties

properties are coded within the class

either as public variables or as

property procedures

operations are actions that can be done

to

or performed by the object they're

sometimes referred to as behaviors

but more commonly they're known as

methods

methods are programs within the class

that are coded either as procedures

or functions a class is a template

for creating objects and it's often

compared with a pastry cutter

because once it's been written it can be

used to create many objects

of the same type in fact a class is

sometimes referred to

as a type each object

is an instance of a class in the

computer's memory

creating an object from a class is

therefore known as

instantiation once these objects have

been created

their properties can be assigned values

making each object of the same type

a unique entity each property is defined

in the class by a property procedure

which may include code to validate a

property value

while it's being assigned this helps to

ensure the integrity of the data

contained within the object

the property values that have been

assigned to an object are collectively

known as

the state of the object

it's also possible to assign values to

properties

while an object is being instantiated by

means of a special method called new

this method is known as the constructor

the second fundamental concept of

object-oriented programming

is encapsulation this means to hide the

complexity of the inner workings of an

object

from the programs and the programmers

that make use of it it's often referred

to as

information hiding because the data

contained within an object

and the functions that manipulate the

data are bound together

and therefore safe from outside

interference

in some big software development

projects

it's common for more experienced

programmers to write the classes

that will be used by the junior

programmers

a class might be made available in the

form of a class

library indeed some software development

companies

specialise in developing new classes to

be used by

other software developers compiled class

libraries protect

their intellectual property

to write code that will create an object

from a class

then set its properties and call its

methods it's not

necessary to understand the inner

workings of the class

all the programmer needs to know is the

name of the class

the properties and methods available and

any data that need to be supplied when

they're called

in other words all our programmer really

needs to know about

is the interface of the class the

implementation code of those properties

and methods

can remain a mystery this greatly

simplifies the use of objects

and helps to ensure that the data and

operations encapsulated within

are safe

the third fundamental concept of

object-oriented programming

is inheritance this means that a class

can derive its methods and properties

from another class inheritance can

result in a hierarchy of classes

for example this person class defines

the methods and properties

of a person object

an employee in a business is also a

person

so through inheritance an employee class

derives the methods and properties of

the person class

an employee is a type of person

a customer of the business is also a

person

so through inheritance a customer class

also derives the methods and properties

of the person class

a customer is a type of person

an employee class can have some extra

properties and methods of its own

it can extend the person class

and so can a customer

but it need not stop there a programmer

is a type of employee and so is a

manager

and a cleaner inheritance defines

type of relationships

the class at the start of the

inheritance hierarchy is called

the base class any class that derives

from another class

is called a sub class any class that is

derived from

is called a superclass

the final fundamental concept of

object-oriented programming

is polymorphism polymorphism

means that a class can implement an

inherited method

in its own way the person class at the

base of this hierarchy

has a method which will save details of

any object

created from the person class perhaps to

a database

thanks to inheritance all of the classes

in this hierarchy

do exactly the same thing but

it may be necessary for a customer's

details

to be saved differently perhaps to a

different database

polymorphism allows for this the

customer class can

override the workings of any method or

property

that it inherits with a new version of

its own

different forms of the same type of

object with the same

interface can behave in different ways

polymorphism literally means many forms

to recap the fundamental concepts of

object-oriented programming

abstraction means to simplify reality

and focus only on the data and processes

that are relevant to the application

being built

encapsulation means that data and the

programs that manipulate those data

are bound together and their complexity

is hidden

inheritance means that a class can

derive its methods and properties

from another class this might result in

an extensive hierarchy

of superclasses and subclasses

polymorphism means that different

subclasses

of the same superclass which therefore

share the same interface

can implement those interfaces in their

own ways

by overriding the code of the methods

they inherit