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Python Basic Object-Oriented Python Emulating Built-ins Emulating Built-ins

Anthony Costanza
Anthony Costanza
2,123 Points

Anybody know what's wrong with this?

Anybody know what's wrong with this?

book.py
class Book:
    def __init__(self, author, title):
        self.author = author
        self.title = title

    def __str__(self):
        return f'{self.author}, {self.title}'

    def __eq__(self, author, title):
        if self.author == self.title:
            return True
        else:
            return False



Book_one = Book('John Green', 'Paper Towns')
bookcase.py
from book import Book


class BookCase:
    def __init__(self):
       self.books = []

    def add_books(self, book):
        self.books.append(book)

1 Answer

eq is used to define what attribute(s) makes two objects of the same class equal. In the video's example, two cars would be equal if they had the same make and model, but were made in different years. In this scenario, you want two separate Book instances to return equal if both the author and the title are the same. Taking this example further, if the object had a 'binding' attribute to store paperback, hardcover, mass market, etc. , this setup would say that two books with the same author and title are still equal even if one is paperback and the other is hardcover.

This challenge question isn't asking you to make the comparison, it's asking you to set up the object to be ready for the comparison (the comparison is happening behind the scenes). In short, your eq should simply return the condition upon which two Book objects should be considered equal. That should look something like this:

    def __eq__(self, other):
        return self.author == other.author and self.title == other.title