Magic / Dunder Methods

class Book:
    def __init__(self, title, author, pages):
        self.title = title
        self.author = author
        self.pages = pages
    
    def __str__(self):  # print() friendly
        return f"'{self.title}' by {self.author}"
    
    def __repr__(self):  # developer friendly
        return f"Book('{self.title}', '{self.author}', {self.pages})"
    
    def __len__(self):
        return self.pages
    
    def __eq__(self, other):
        return self.title == other.title and self.author == other.author
    
    def __lt__(self, other):
        return self.pages < other.pages
    
    def __contains__(self, word):
        return word.lower() in self.title.lower()

b1 = Book("Python Crash Course", "Eric Matthes", 544)
b2 = Book("Automate the Boring Stuff", "Al Sweigart", 592)

print(b1)          # __str__
print(repr(b1))    # __repr__
print(len(b1))     # __len__: 544
print(b1 < b2)     # __lt__: True
print("Python" in b1)  # __contains__: True

# Sortable!
books = [b2, b1]
books.sort()
for b in books:
    print(f"  {b} ({len(b)} pages)")