2. Classes and Instances | Learning Object-Oriented Programming

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Learning Object-Oriented Programming

By : Gaston C. Hillar

3.3 (3)

Learning Object-Oriented Programming

3.3 (3)

By: Gaston C. Hillar

Overview of this book

If you're a Python, JavaScript, or C# developer and want to learn the basics of object-oriented programming with real-world examples, then this book is for you.

Preface

Preface

What this book covers

What you need for this book

Who this book is for

Conventions

Reader feedback

Customer support

Free Chapter

1. Objects Everywhere

1. Objects Everywhere

Recognizing objects from nouns

Generating blueprints for objects

Recognizing attributes/fields

Recognizing actions from verbs – methods

Organizing the blueprints – classes

Object-oriented approaches in Python, JavaScript, and C#

Summary

2. Classes and Instances

2. Classes and Instances

Understanding classes and instances

Understanding constructors and destructors

Declaring classes in Python

Customizing constructors in Python

Customizing destructors in Python

Creating instances of classes in Python

Declaring classes in C#

Customizing constructors in C#

Customizing destructors in C#

Creating instances of classes in C#

Understanding that functions are objects in JavaScript

Working with constructor functions in JavaScript

Creating instances in JavaScript

Summary

3. Encapsulation of Data

3. Encapsulation of Data

Understanding the different members of a class

Protecting and hiding data

Working with properties

Understanding the difference between mutability and immutability

Encapsulating data in Python

Encapsulating data in C#

Encapsulating data in JavaScript

Summary

4. Inheritance and Specialization

4. Inheritance and Specialization

Using classes to abstract behavior

Understanding inheritance

Understanding method overloading and overriding

Understanding operator overloading

Taking advantage of polymorphism

Working with simple inheritance in Python

Working with simple inheritance in C#

Working with the prototype-based inheritance in JavaScript

Summary

5. Interfaces, Multiple Inheritance, and Composition

5. Interfaces, Multiple Inheritance, and Composition

Understanding the requirement to work with multiple base classes

Working with multiple inheritance in Python

Interfaces and multiple inheritance in C#

Working with composition in JavaScript

Summary

6. Duck Typing and Generics

6. Duck Typing and Generics

Understanding parametric polymorphism and duck typing

Working with duck typing in Python

Working with generics in C#

Working with duck typing in JavaScript

Summary

7. Organization of Object-Oriented Code

7. Organization of Object-Oriented Code

Thinking about the best ways to organize code

Organizing object-oriented code in Python

Organizing object-oriented code in C#

Organizing object-oriented code in JavaScript

Summary

8. Taking Full Advantage of Object-Oriented Programming

8. Taking Full Advantage of Object-Oriented Programming

Putting together all the pieces of the object-oriented puzzle

Refactoring existing code in Python

Refactoring existing code in C#

Refactoring existing code in JavaScript

Summary

Index

Index

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Customizing destructors in Python

We want to know when the instances of the Rectangle class are removed from memory, that is, when the objects become inaccessible and get deleted by the garbage-collection mechanism. However, it is very important to notice that the ways in which garbage collection works depends on the implementation of Python. Remember that, Python runs on a wide variety of platforms.

Before Python removes an instance from memory, it calls the __del__ method. Thus, we can use this method to add any code we want to run before the instance is destroyed. We can think of the __del__ method as the equivalent of a destructor in other object-oriented programming languages.

The following lines declare a __del__ method within the body of the Rectangle class. Remember that Python always receives self as the first argument for any instance method:

def __del__(self):
        print('A Rectangle instance is being destroyed.')

The following lines create two instances of the Rectangle class...

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