When to use which creational pattern in LLD - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to choose the creational pattern that provides a single instance.

LLD

class DatabaseConnection:
    _instance = None

    def __new__(cls):
        if cls._instance is None:
            cls._instance = super().__new__(cls)
        return [1]

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

Acls._instance

Bself

CDatabaseConnection

DNone

Attempts:

3 left

💡 Hint

Common Mistakes

Returning self instead of the stored instance

Returning None causing errors

The Singleton pattern ensures only one instance exists. Returning cls._instance provides that single instance.

2fill in blank

medium

Complete the code to use the Factory Method pattern to create objects without specifying the exact class.

LLD

class AnimalFactory:
    def create_animal(self, animal_type):
        if animal_type == 'dog':
            return Dog()
        elif animal_type == 'cat':
            return [1]()

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

AAnimal

BDog

CCat

DPet

Attempts:

3 left

💡 Hint

Common Mistakes

Returning Dog instead of Cat

Returning a base class instead of specific class

The Factory Method creates objects based on input. To create a cat, return Cat().

3fill in blank

hard

Fix the error in the Builder pattern code to correctly build a product step by step.

LLD

class CarBuilder:
    def __init__(self):
        self.car = Car()

    def add_wheels(self):
        self.car.wheels = 4

    def add_engine(self):
        self.car.engine = 'V8'

    def get_car(self):
        return [1]

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

Aself

Bcar

CCar()

Dself.car

Attempts:

3 left

💡 Hint

Common Mistakes

Returning a new Car instead of the built one

Returning undefined variable

The method should return the built car object stored in self.car.

4fill in blank

hard

Fill both blanks to complete the Abstract Factory pattern that creates families of related objects.

LLD

class GUIFactory:
    def create_button(self):
        return [1]()

    def create_checkbox(self):
        return [2]()

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

AWindowsButton

BLinuxButton

CWindowsCheckbox

DLinuxCheckbox

Attempts:

3 left

💡 Hint

Common Mistakes

Mixing Windows and Linux classes

Using unrelated classes

Abstract Factory creates related objects. For Windows GUI, create WindowsButton and WindowsCheckbox.

5fill in blank

hard

Fill all three blanks to complete the Prototype pattern code that clones objects.

LLD

class Document:
    def __init__(self, content):
        self.content = content

    def clone(self):
        return Document([1])

original = Document('Report')
copy = original.clone()
copy.content = [2]
print(original.content, copy.content)  # [3]

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

Aself.content

B'Summary'

CReport Summary

Dcontent

Attempts:

3 left

💡 Hint

Common Mistakes

Passing undefined variable to clone

Changing original content instead of copy

The clone method copies the content from self.content. Then we change the copy's content to 'Summary'. The print shows original and copy contents.