Object initialization flow in Python - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to define the constructor method for a class.

Python

class Car:
    def [1](self, make, model):
        self.make = make
        self.model = model

Drag options to blanks, or click blank then click option'

Astart

Binit

Cconstructor

D__init__

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'init' without underscores.

Using 'constructor' which is not a Python method name.

The constructor method in Python classes is named __init__. It runs when an object is created.

2fill in blank

medium

Complete the code to create an object of the class Car.

Python

my_car = Car([1], 'Model S')

Drag options to blanks, or click blank then click option'

A'Tesla'

BTesla

CCar

D"Model S"

Attempts:

3 left

💡 Hint

Common Mistakes

Not using quotes around string arguments.

Passing the class name instead of a string.

When creating an object, string arguments must be in quotes. Here, 'Tesla' is the make.

3fill in blank

hard

Fix the error in the method to correctly initialize the attribute.

Python

class Person:
    def __init__(self, name):
        self.[1] = name

p = Person('Alice')
print(p.name)

Drag options to blanks, or click blank then click option'

AName

Bnam

Cname

Dnames

Attempts:

3 left

💡 Hint

Common Mistakes

Using capitalized or misspelled attribute names.

Mismatch between attribute and print statement.

The attribute name must exactly match the one used when accessing it. Here, self.name matches p.name.

4fill in blank

hard

Fill both blanks to create a class with an attribute and a method that returns it.

Python

class Book:
    def __init__(self, title):
        self.[1] = title
    def get_[2](self):
        return self.title

Drag options to blanks, or click blank then click option'

Atitle

Bname

Attempts:

3 left

💡 Hint

Common Mistakes

Using different names for attribute and method.

Mismatch between attribute and method names.

The attribute is named title, so the method should be get_title to match.

5fill in blank

hard

Fill all three blanks to initialize an object with two attributes and a method that returns a formatted string.

Python

class Student:
    def __init__(self, name, age):
        self.[1] = name
        self.[2] = age
    def info(self):
        return f"Name: {self.[3], Age: {self.age}"

Drag options to blanks, or click blank then click option'

Aname

Bage

Dstudent

Attempts:

3 left

💡 Hint

Common Mistakes

Using different names for attributes and in the method.

Forgetting to initialize both attributes.

The attributes name and age must be initialized and used consistently in the method.

Practice

1. What is the purpose of the __init__ method in a Python class?

easy

A. To delete an object when it is no longer needed

B. To define a class-level variable

C. To initialize a new object when it is created

D. To print the object details

Solution

1. Step 1: Understand the role of __init__

   The __init__ method runs automatically when a new object is created from a class.

2. Step 2: Identify what __init__ does

   It sets up the initial state of the object by assigning values to its attributes.

3. Final Answer:

   To initialize a new object when it is created -> Option C

4. Quick Check:

   __init__ initializes objects [OK]

Hint: Remember: __init__ sets up new objects automatically [OK]

Common Mistakes:

• Confusing __init__ with __del__
• Thinking __init__ is for printing
• Believing __init__ defines class variables

2. Which of the following is the correct syntax to define an __init__ method that takes a parameter name in a Python class?

easy

A. def __init__(self, name):

B. def __init__(name):

C. def init(self, name):

D. def __init__(self):

Solution

1. Step 1: Recall __init__ method signature

   The first parameter must be self to refer to the new object.

2. Step 2: Check parameter list

   To accept a name argument, it must be added after self.

3. Final Answer:

   def __init__(self, name): -> Option A

4. Quick Check:

   First param is self, then others [OK]

Hint: Always put self first in method parameters [OK]

Common Mistakes:

• Omitting self parameter
• Using init instead of __init__
• Missing parameters after self

3. What will be the output of this code?

class Car:
    def __init__(self, brand):
        self.brand = brand

my_car = Car('Toyota')
print(my_car.brand)

medium

A. Car

B. Toyota

C. brand

D. Error

Solution

1. Step 1: Understand object creation

   Creating my_car = Car('Toyota') calls __init__ with 'Toyota' as brand.

2. Step 2: Check attribute assignment and print

   The brand attribute of my_car is set to 'Toyota', so printing my_car.brand outputs 'Toyota'.

3. Final Answer:

   Toyota -> Option B

4. Quick Check:

   Attribute value prints 'Toyota' [OK]

Hint: Print attribute after init to see assigned value [OK]

Common Mistakes:

• Expecting class name instead of attribute value
• Confusing attribute name with value
• Thinking print causes error

4. What is wrong with this class definition?

class Person:
    def __init__(self, age):
        age = age

p = Person(30)
print(p.age)

medium

A. The attribute age is not assigned to self

B. The __init__ method is missing self parameter

C. The print statement syntax is incorrect

D. The class name should be lowercase

Solution

1. Step 1: Check attribute assignment inside __init__

   The code assigns age = age, which only reassigns the local variable, not the object's attribute.

2. Step 2: Understand how to assign attributes

   To store the value in the object, it should be self.age = age.

3. Final Answer:

   The attribute age is not assigned to self -> Option A

4. Quick Check:

   Use self.attribute = value to save data [OK]

Hint: Always assign attributes with self.attribute = value [OK]

Common Mistakes:

• Forgetting self in attribute assignment
• Thinking local variable sets object attribute
• Ignoring error messages about missing attributes

5. Given this class:

class Book:
    def __init__(self, title, author='Unknown'):
        self.title = title
        self.author = author

b1 = Book('Python 101')
b2 = Book('Learn AI', 'Alice')

What are the values of b1.author and b2.author?

hard

A. Both b1.author and b2.author are 'Unknown'

B. b1.author is 'Python 101', b2.author is 'Learn AI'

C. b1.author is None, b2.author is 'Alice'

D. b1.author is 'Unknown', b2.author is 'Alice'

Solution

1. Step 1: Understand default parameter usage

   The author parameter has a default value 'Unknown', used if no argument is given.

2. Step 2: Check object creation

   b1 is created with only title, so author defaults to 'Unknown'. b2 provides 'Alice' explicitly.

3. Final Answer:

   b1.author is 'Unknown', b2.author is 'Alice' -> Option D

4. Quick Check:

   Default params fill missing arguments [OK]

Hint: Default values apply when argument is missing [OK]

Common Mistakes:

• Assuming missing argument becomes None
• Mixing title and author values
• Forgetting default parameter behavior