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añadido ejercicio 42.1-init_and_str_methods
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# `042.1` `__init__` and `__str__` methods
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Normalmente, al trabajar con clases, te encontrarás con métodos de este estilo `__<método>__`; estos son conocidos como "métodos mágicos". Existen varios de ellos, y cada uno desempeña una función específica. En esta ocasión, nos enfocaremos en aprender dos de los más fundamentales.
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El método mágico `__init__` es esencial para la inicialización de objetos dentro de una clase. Se ejecuta automáticamente cuando se crea una nueva instancia de la clase, permitiendo la asignación de valores iniciales a los atributos del objeto.
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El método `__str__` se utiliza para proporcionar una representación de cadena legible de la instancia, permitiendo personalizar la salida cuando se imprime el objeto. Esto es especialmente útil para mejorar la legibilidad del código y facilitar la depuración, ya que define una versión amigable para humanos de la información contenida en el objeto.
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## 📎 Ejemplo:
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```py
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class Person:
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def __init__(self, name, age, gender):
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self.name = name
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self.age = age
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self.gender = gender
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def __str__(self):
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return f"{self.name}, {self.age} years old, {self.gender}"
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# Create an instance of the Person class
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person1 = Person("Juan", 25, "Male")
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# Print the information of the person using the __str__ method
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print(person1) # Output: Juan, 25 years old, Male
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```
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## 📝 Instrucciones:
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1. Crea una clase llamada `Book` que tenga los métodos `__init__` y `__str__`.
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2. El método `__init__` debe inicializar los atributos `title`, `author` y `year`.
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3. El método `__str__` debe devolver una cadena que represente la información de una instancia del siguiente libro de esta manera:
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```py
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book1 = ("The Great Gatsby", "F. Scott Fitzgerald", 1925)
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print(book1)
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# Output:
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#
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# Book Title: The Great Gatsby
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# Author: F. Scott Fitzgerald
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# Year: 1925
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```
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## 💡 Pistas:
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+ Utiliza el método `__init__` para inicializar los atributos de la instancia.
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+ Utiliza el método `__str__` para proporcionar una representación de cadena legible de la instancia.
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+ Para hacer saltos de línea dentro de un string puedes usar los siguientes caracteres `\n`.
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# `042.1` `__init__` and `__str__` methods
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Typically, when working with classes, you will encounter methods of the form `__<method>__`; these are known as "magic methods." There are a lot of them, each serving a specific purpose. This time, we will focus on learning two of the most fundamental ones.
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The magic method `__init__` is essential for the initialization of objects within a class. It is automatically executed when a new instance of the class is created, allowing for the assignment of initial values to the object's attributes.
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The `__str__` method is used to provide a readable string representation of the instance, allowing customization of the output when the object is printed. This is especially useful for improving code readability and facilitating debugging, as it defines a human-friendly version of the information contained in the object.
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## 📎 Example:
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```py
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class Person:
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def __init__(self, name, age, gender):
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self.name = name
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self.age = age
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self.gender = gender
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def __str__(self):
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return f"{self.name}, {self.age} years old, {self.gender}"
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# Create an instance of the Person class
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person1 = Person("Juan", 25, "Male")
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# Print the information of the person using the __str__ method
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print(person1) # Output: Juan, 25 years old, Male
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```
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## 📝 Instructions:
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1. Create a class called `Book` that has the `__init__` and `__str__` methods.
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2. The `__init__` method should initialize the `title`, `author`, and `year` attributes.
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3. The `__str__` method should return a string representing the information of an instance of the following book in this manner:
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```py
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book1 = ("The Great Gatsby", "F. Scott Fitzgerald", 1925)
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print(book1)
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# Output:
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#
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# Book Title: The Great Gatsby
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# Author: F. Scott Fitzgerald
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# Year: 1925
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```
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## 💡 Hints:
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+ Use the `__init__` method to initialize the instance's attributes.
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+ Use the `__str__` method to provide a readable string representation of the instance.
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+ To create line breaks within a string, you can use the `\n` characters.
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# Your code here
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# Your code here
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class Book:
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def __init__(self, title, author, year):
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self.title = title
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self.author = author
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self.year = year
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def __str__(self):
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return f"Book Title: {self.title}\nAuthor: {self.author}\nYear: {self.year}"
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book1 = Book("The Great Gatsby", "F. Scott Fitzgerald", 1925)
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print(book1)
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import pytest
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from app import Book
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@pytest.mark.it("The Book class exists")
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def test_book_class_exists():
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try:
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assert Book
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except AttributeError:
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raise AttributeError("The class 'Book' should exist in app.py")
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@pytest.mark.it("The Book class has the __init__ method")
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def test_book_has_init_method():
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assert hasattr(Book, "__init__")
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@pytest.mark.it("The __init__ method initializes the title, author, and year attributes")
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def test_init_method_initializes_attributes():
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book = Book("The Great Gatsby", "F. Scott Fitzgerald", 1925)
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assert hasattr(book, "title")
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assert hasattr(book, "author")
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assert hasattr(book, "year")
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@pytest.mark.it("The Book class has the __str__ method")
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def test_book_has_str_method():
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assert hasattr(Book, "__str__")
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@pytest.mark.it("The __str__ method returns the expected string")
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def test_str_method_returns_expected_string(capsys):
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book = Book("The Great Gatsby", "F. Scott Fitzgerald", 1925)
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print(book)
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captured = capsys.readouterr()
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expected_output = "Book Title: The Great Gatsby\nAuthor: F. Scott Fitzgerald\nYear: 1925\n"
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assert captured.out == expected_output
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