null created by anonymous - https://repl.it/KhuA/17

main.py

# import di classi esterne al mio file principale
from module import Book
from module import Dictionary

book = Book("Moby Dick", "Loomings. \
Call me Ishmael. Some years ago—never mind how\
long precisely...", 500)

book.read()
print("Implementation of special method __len__:")
for x in range(len(book)):
	print(x + 1, end=" ")
print("pages!")

myFirstDictionary = Dictionary("Garzanti", "Apple = mela, mela = apple", 1, "English -> Italian and viceversa")
print("The Dictionary is a Book: ", issubclass(Dictionary, Book))
print("myFirstDictionary is a Dictionary: ", isinstance(myFirstDictionary, Dictionary))
print("myFirstDictionary is a Book: ", isinstance(myFirstDictionary, Book))

print("I'm printing on a file...")

#with construct
with open("myFile.txt", "a") as file:
	print("I've printed on a filme many times!:D", file=file) # a = append: aggiunta non in sovrascrittura!

print("Printing my book:\n", book)
print("Calling private method from other function:")
book.callMyPrivateMethod()
print("Calling it directly:")
book.__privateMethod()

module.py

class Book:
	def __init__(self, title, body, pages):
		self.title = title
		self.body = body
		self.pages = pages
	
	def read(self):
		print(self.body)
	
	def __privateMethod(self):
		print("You can't call me from outside!")
		
	def callMyPrivateMethod(self):
		self.__privateMethod()
		
	def __len__(self):
		return self.pages
		
	def __str__(self):
		return "Title: {0}\nBody: {1}\nFor {2} pages...:O".format(self.title, self.body, self.pages)

class Dictionary(Book):
	def __init__(self, title, body, pages, languages):
		# calling super-constructor
		super(Dictionary, self).__init__(title, body, pages)
		self.languages = languages