Table of Contents

1. Challenge

   Introduction

   Lab Overview

   In this hands-on project, you will construct an object-oriented "library system" with Python.

   You will design three core classes—Book, Borrower, and Library—to simulate fundamental library operations, such as adding books, checking out, and returning items.

   When you are finished you will have a solid grasp of Python's class structures, methods, and object interactions.

   When you are done click Run to see the application's output.

   Book Class

   • The Book class will represent individual books. Each book will have attributes such as title, author and available.

   Borrower Class

   • The Borrower class will represent people who come to borrow books. Each Borrower will have attributes like name and borrowed_books, which will hold a list of books currently borrowed by them.

   Library Class

   • The Library class will act as the main hub where the operations take place. This class will have attributes such as book_list (a list of all books in the library) and methods to add books, check out books to borrowers, and receive returned books.

   Interactions Between Objects

   • As you develop these classes, you'll also implement methods that allow these objects to interact. For example, when a borrower checks out a book, the availability of the book changes, and the book gets added to the borrower's borrowed_books list. Similarly, when a book is returned, its availability changes again, and it gets removed from the borrower's list.

   If you're ready to get started, proceed to the next steps.

2. Challenge

   Creating a Book Class

   Book Class Overview

   The __init__ method:

   This is the initializer (or constructor) method in Python, automatically invoked when you create a new instance of the Book class.

   Parameters:

   • self: A reference to the instance of the class Book being created. In Python, it's explicitly declared, whereas in many other object-oriented programming languages, it's a hidden parameter passed to methods and defined by the system.

   • title: An external parameter provided when you create a new instance of the Book class. It represents the title of the book.

   • author: Another external parameter you'd provide when instantiating the Book class. It represents the author of the book.

   Attributes:

   Within the __init__ method, three instance attributes are initialized:

   • self.title = title: Sets the title attribute of the Book object to the value passed during its instantiation.

   • self.author = author: Sets the author attribute of the Book object to the value passed during instantiation.

   • self.available = True: Initializes the available attribute of the Book object to True, indicating that the book is available by default when it's created.

3. Challenge

   Creating a Borrower Class

   Borrower Class Overview

   The __init__ method: This is a special method in Python that is automatically called when you create a new instance of a class (i.e., when you instantiate the class).

   Parameters:

   • self: This is a reference to the instance of the class Borrower being created. In most object-oriented programming languages, this is passed to the methods as a hidden parameter that is defined by the system. But in Python, it must be explicitly declared.

   • name: This is an external parameter that you would provide when you create a new instance of the Borrower class. It represents the name of the borrower.

   Attributes:

   Within the __init__ method, two instance attributes are being set:

   self.name = name: This sets the name attribute of the Borrower object to the value passed when the object is instantiated.

   self.borrowed_books = []: This initializes an empty list for the borrowed_books attribute. This list is meant to store books that the borrower has currently borrowed.

4. Challenge

   Creating a Library Class

   Library Class Overview

   The __init__ method:

   This is the initializer (or constructor) method in Python, automatically invoked when you create a new instance of the Library class.

   Attributes:

   • self.inventory = []: Initializes the inventory attribute of the Library object as an empty list. This list will hold all the books in the library.

   Methods:

   • add_book(self, book)
   • checkout_book(self, book, borrower)
   • return_book(self, book, borrower)
   • list_available_books(self)
5. Challenge

   Library Class Methods

   Adding and Checking Out Books

   add_book(self, book):

   • Purpose: Adds a book to the library's inventory.

   • Parameter:

     • book: The book object that you want to add to the library's inventory.

   • Action: Uses the append method to add the provided book to the inventory list.

   checkout_book(self, book, borrower):

   • Purpose: Allows a borrower to check out a book from the library, provided the book is available.

   • Parameters:

     • book: The book object that the borrower wants to check out.
     • borrower: The borrower object representing the person checking out the book.

   • Action: If the book is available, it changes the book's available attribute to False, adds the book to the borrower's borrowed_books list, and displays a message if the book is not available.

6. Challenge

   Library Methods Continued

   Returning and Listing All Books

   return_book(self, book, borrower):

   • Purpose: Allows a borrower to return a book they've checked out from the library.

   • Parameters:

     • book: The book object being returned.
     • borrower: The borrower object representing the person returning the book.

   • Action: If the book is in the borrower's borrowed_books list, it changes the book's available attribute to True and removes the book from the borrower's list. If the borrower didn't borrow that particular book, a message is displayed.

   list_available_books(self):

   • Purpose: Lists the titles of all available books in the library.

   • Action: Uses list comprehension to return a list of titles of all books in the inventory that are currently available.

7. Challenge

   Using the Library System

   Using The Library

   If you're classes are complete ,you should be able to click Run in your terminal and see the following output.

   Initial books in the library:
   - The Great Gatsby
   - 1984
   - Brave New World
   - Pride and Prejudice
   
   John tries to borrow 'The Great Gatsby'...
   
   Jane tries to borrow 'The Great Gatsby'...
   The Great Gatsby is not available.
   
   Books John has borrowed:
   - The Great Gatsby
   
   Available books in the library:
   ['1984', 'Brave New World', 'Pride and Prejudice']
   
   Jane tries to return 'The Great Gatsby'...
   Jane Smith didn't borrow The Great Gatsby.
   
   John returns 'The Great Gatsby'...
   
   Jane tries again to borrow 'The Great Gatsby'...
   
   Books Jane has borrowed:
   - The Great Gatsby
   
   Current available books in the library:
   ['1984', 'Brave New World', 'Pride and Prejudice']
   

   Feel free to experiment, add books, check them out and use the methods from the Library class.