ExamAdept

Consider the following Python class:

class BankAccount:
    def __init__(self, balance):
        self._balance = balance

    @property
    def balance(self):
        return self._balance

What does the @property decorator do in this code?

A:

It creates a new instance of the class

B:

It defines a private variable

C:

It provides a setter method for the balance variable

D:

It allows read-only access to the balance variable

Answer: D

The @property decorator is used to create a read-only property 'balance', providing controlled access to the private variable '_balance'.

📖

What is the purpose of the following Python code?

class TemperatureConverter:
    def __init__(self, celsius):
        self._celsius = celsius

    @property
    def fahrenheit(self):
        return self._celsius * 9/5 + 32

A:

To create a new instance of the class

B:

To provide a setter method for the celsius variable

C:

To calculate and provide read-only access to the temperature in Fahrenheit

D:

To expose all internal details of the class

Answer: C

The @property decorator is used to create a read-only property 'fahrenheit' that calculates the temperature in Fahrenheit based on the stored Celsius value.

📖

What is the advantage of encapsulating a class attribute with a double underscore prefix, such as __count?

class MyClass:
    __count = 0

    def increment_count(self):
        MyClass.__count += 1

A:

It allows unrestricted access to __count

B:

It improves code maintainability by hiding implementation details

C:

It exposes all internal details of __count

D:

It creates a global variable

Answer: B

Encapsulation with a double underscore prefix improves code maintainability by hiding the implementation details of the class attribute __count.

📖

How can encapsulation be achieved in Python to provide read-only access to a variable?

class Example:
    def __init__(self):
        self.__value = 42

A:

Make __value a global variable

B:

Create a getter method for __value

C:

Use a single underscore prefix for __value

D:

Make __value a public variable

Answer: B

To provide read-only access to a variable, a getter method can be created to retrieve the value.

📖

Consider the following Python code:

class Person:
    def __init__(self, name, __age):
        self.name = name
        self.__age = __age

    def get_age(self):
        return self.__age

What is the purpose of the get_age() method?

A:

To set the age of a person

B:

To retrieve the age of a person

C:

To delete the age of a person

D:

To create a new instance of the class

Answer: B

The get_age() method is designed to retrieve the private variable __age, demonstrating encapsulation by providing controlled access.

📖

Questions for: Encapsulation