Exercise: Encapsulation

Questions for: Encapsulation

Consider the following Python code: 
class Triangle:
    def __init__(self, __base, __height):
        self.__base = __base
        self.__height = __height

    def calculate_area(self):
        return 0.5 * self.__base * self.__height
What is the purpose of the calculate_area() method?
A:
To retrieve the area of the triangle
B:
To set a new area for the triangle
C:
To calculate the area of the triangle
D:
To expose all internal details of the class
Answer: C
The calculate_area() method calculates and returns the area of the triangle, demonstrating encapsulation.
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How can encapsulation be enforced in Python to make a variable 'product_code' accessible only within its own class? 
class Product:
    def __init__(self, product_code, __price):
        self.product_code = product_code
        self.__price = __price
A:
Use a getter method for 'product_code'
B:
Add a single underscore prefix before 'product_code'
C:
Make 'product_code' a global variable
D:
Add a double underscore prefix before 'product_code'
Answer: D
Adding a double underscore prefix before 'product_code' makes it a private variable, enforcing encapsulation within the class.
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What is the primary purpose of the following Python class? 
class Car:
    def __init__(self, model, __speed):
        self.model = model
        self.__speed = __speed

    def get_speed(self):
        return self.__speed
A:
To create a new instance of the class
B:
To provide controlled access to the 'speed' variable
C:
To define a public variable 'speed'
D:
To allow unrestricted access to the 'speed' variable
Answer: B
The get_speed() method provides controlled and read-only access to the private variable '__speed', demonstrating encapsulation.
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In Python, what is the benefit of using a private variable with a double underscore prefix, such as __inventory_count? 
class Product:
    __inventory_count = 0

    def update_inventory(self, count):
        Product.__inventory_count += count
A:
It improves code maintainability by hiding implementation details
B:
It allows unrestricted access to __inventory_count
C:
It exposes all internal details of __inventory_count
D:
It creates a global variable
Answer: A
Encapsulation with a double underscore prefix improves code maintainability by hiding the implementation details of the class attribute __inventory_count.
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Consider the following Python code: 
class Rectangle:
    def __init__(self, __length, __width):
        self.__length = __length
        self.__width = __width

    def calculate_area(self):
        return self.__length * self.__width
What is the purpose of the calculate_area() method?
A:
To retrieve the area of the rectangle
B:
To set a new area for the rectangle
C:
To calculate the area of the rectangle
D:
To expose all internal details of the class
Answer: C
The calculate_area() method calculates and returns the area of the rectangle, demonstrating encapsulation.
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