Why multiple inheritance exists in Python - Test Your Understanding

Practice - 5 Tasks

1fill in blank

easy

Complete the code to define a class that inherits from two parent classes.

Python

class Child([1]):
    pass

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

AParent1, Parent2

BParent1

CParent2

DChild

Attempts:

3 left

💡 Hint

Common Mistakes

Forgetting to separate parent classes with commas.

Using only one parent class name when multiple are needed.

Multiple inheritance allows a class to inherit from more than one parent class by listing them separated by commas inside the parentheses.

2fill in blank

medium

Complete the code to call the constructor of both parent classes inside the child class.

Python

class Child(Parent1, Parent2):
    def __init__(self):
        [1]

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Asuper().__init__()

BParent1.__init__(self)

CParent1.__init__(self) Parent2.__init__(self)

DParent2.__init__(self)

Attempts:

3 left

💡 Hint

Common Mistakes

Calling only one parent's __init__ method.

Using super() which may not call all parent constructors in multiple inheritance.

When using multiple inheritance, you often need to call each parent class's constructor explicitly to initialize them properly.

3fill in blank

hard

Fix the error in the method resolution order by completing the code to call super() correctly in multiple inheritance.

Python

class Parent1:
    def greet(self):
        print('Hello from Parent1')

class Parent2:
    def greet(self):
        print('Hello from Parent2')

class Child(Parent1, Parent2):
    def greet(self):
        [1]
        print('Hello from Child')

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Asuper().greet()

BParent1.greet(self)

CParent2.greet(self)

Dgreet()

Attempts:

3 left

💡 Hint

Common Mistakes

Calling a specific parent method directly, which can break the method resolution order.

Not calling any parent method at all.

Using super() in multiple inheritance respects the method resolution order and calls the next method in line properly.

4fill in blank

hard

Fill both blanks to create a dictionary comprehension that maps words to their lengths only if the length is greater than 3.

Python

words = ['tree', 'cat', 'house', 'dog']
lengths = {word: [1] for word in words if [2]

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Alen(word)

Blen(word) > 3

Cword > 3

Dword

Attempts:

3 left

💡 Hint

Common Mistakes

Using the word itself instead of its length.

Comparing the word string directly to a number.

The dictionary comprehension maps each word to its length using len(word), and includes only words whose length is greater than 3.

5fill in blank

hard

Fill all three blanks to create a dictionary comprehension that maps uppercase keys to values only if the value is positive.

Python

data = {'a': 1, 'b': -2, 'c': 3}
result = { [1]: [2] for k, v in data.items() if v [3] 0}

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Ak.upper()

Bv

C>

Dk

Attempts:

3 left

💡 Hint

Common Mistakes

Using original keys without converting to uppercase.

Using incorrect comparison operators.

Including negative or zero values.

The comprehension creates a new dictionary with keys converted to uppercase and includes only items where the value is greater than zero.

Practice

1. Why does Python support multiple inheritance?

easy

A. To allow a class to inherit features from more than one parent class

B. To make code run faster

C. To prevent any class from having methods

D. To force all classes to have the same methods

Solution

1. Step 1: Understand inheritance basics

   Inheritance lets a class use methods and properties from a parent class.

2. Step 2: Recognize multiple inheritance purpose

   Multiple inheritance allows a class to get features from more than one parent, combining abilities without rewriting code.

3. Final Answer:

   To allow a class to inherit features from more than one parent class -> Option A

4. Quick Check:

   Multiple inheritance = inherit from multiple parents [OK]

Hint: Multiple inheritance means many parents, many features [OK]

Common Mistakes:

• Thinking it makes code faster
• Believing it removes methods
• Assuming all classes become identical

2. Which of the following is the correct syntax to define a class Child that inherits from two parent classes Parent1 and Parent2?

easy

A. class Child : Parent1, Parent2

B. class Child inherits Parent1, Parent2:

C. class Child -> Parent1, Parent2:

D. class Child(Parent1, Parent2):

Solution

1. Step 1: Recall Python class inheritance syntax

   In Python, parent classes are listed inside parentheses after the class name.

2. Step 2: Identify correct syntax for multiple inheritance

   Multiple parents are separated by commas inside the parentheses.

3. Final Answer:

   class Child(Parent1, Parent2): -> Option D

4. Quick Check:

   Parents in parentheses, comma separated [OK]

Hint: Use parentheses with commas for multiple parents [OK]

Common Mistakes:

• Using 'inherits' keyword (not Python syntax)
• Using colon instead of parentheses
• Using arrow '->' which is invalid

3. What will be the output of this code?

class A:
    def greet(self):
        return 'Hello from A'

class B:
    def greet(self):
        return 'Hello from B'

class C(A, B):
    pass

obj = C()
print(obj.greet())

medium

A. Hello from A

B. Error: Method greet not found

C. Hello from C

D. Hello from B

Solution

1. Step 1: Understand method resolution order (MRO)

   Python looks for methods in the order of parent classes listed. Here, C inherits from A first, then B.

2. Step 2: Determine which greet method is called

   Since A is first, C uses A's greet method, returning 'Hello from A'.

3. Final Answer:

   Hello from A -> Option A

4. Quick Check:

   MRO uses first parent method [OK]

Hint: First parent class method is used in conflicts [OK]

Common Mistakes:

• Choosing method from second parent
• Expecting child's own method when none defined
• Thinking it causes error

4. Find the error in this code that tries to use multiple inheritance:

class X:
    def method(self):
        return 'X'

class Y:
    def method(self):
        return 'Y'

class Z(X Y):
    pass

medium

A. Method names must be different in multiple inheritance

B. Missing comma between parent classes in class Z definition

C. Classes cannot have methods with the same name

D. class Z should inherit only one class

Solution

1. Step 1: Check class Z syntax

   Parent classes must be separated by commas inside parentheses.

2. Step 2: Identify missing comma

   Code has 'class Z(X Y):' missing comma between X and Y.

3. Final Answer:

   Missing comma between parent classes in class Z definition -> Option B

4. Quick Check:

   Parents separated by commas [OK]

Hint: Separate parent classes with commas [OK]

Common Mistakes:

• Thinking method names must differ
• Believing multiple methods cause error
• Assuming only one parent allowed

5. You want to create a class SmartPhone that has features from both Camera and Phone classes. Which is the best reason to use multiple inheritance here?

hard

A. To make the phone run faster

B. To avoid creating any methods in SmartPhone

C. To combine camera and phone features without rewriting their code

D. To force Camera and Phone to share the same methods

Solution

1. Step 1: Understand the goal of SmartPhone class

   SmartPhone needs to have both camera and phone abilities.

2. Step 2: Recognize multiple inheritance benefit

   Using multiple inheritance lets SmartPhone reuse code from Camera and Phone classes without rewriting.

3. Final Answer:

   To combine camera and phone features without rewriting their code -> Option C

4. Quick Check:

   Multiple inheritance = reuse multiple parents' features [OK]

Hint: Use multiple inheritance to reuse code from many classes [OK]

Common Mistakes:

• Thinking it improves speed
• Believing it removes need for methods
• Assuming it forces method sharing