Software engineering principles - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to identify the principle that encourages breaking a program into smaller parts.

Software Engineering

The principle of [1] suggests dividing software into smaller, manageable pieces.

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

AModularity

BEncapsulation

CInheritance

DPolymorphism

Attempts:

3 left

💡 Hint

Common Mistakes

Confusing modularity with inheritance.

Thinking encapsulation means dividing code into parts.

Modularity means breaking a program into smaller parts or modules that can be developed and tested independently.

2fill in blank

medium

Complete the code to name the principle that hides internal details from the user.

Software Engineering

The principle of [1] protects data by hiding internal details and exposing only necessary parts.

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

ACoupling

BAbstraction

CCohesion

DEncapsulation

Attempts:

3 left

💡 Hint

Common Mistakes

Mixing up encapsulation with abstraction.

Choosing cohesion instead, which is about relatedness of tasks.

Encapsulation means hiding the internal state and requiring all interaction to be performed through an object's methods.

3fill in blank

hard

Fix the error in naming the principle that allows objects to take many forms.

Software Engineering

The principle of [1] allows objects to be treated as instances of their parent class or their own class.

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

APolymorphism

BInheritance

CModularity

DAbstraction

Attempts:

3 left

💡 Hint

Common Mistakes

Confusing polymorphism with inheritance.

Choosing modularity which is about dividing code.

Polymorphism allows objects to be accessed through references of their parent class, enabling different behaviors.

4fill in blank

hard

Fill both blanks to complete the principle that measures how strongly components depend on each other.

Software Engineering

Low [1] and high [2] are desired for good software design.

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

Acoupling

Binheritance

Ccohesion

Dpolymorphism

Attempts:

3 left

💡 Hint

Common Mistakes

Mixing up coupling and cohesion.

Choosing inheritance or polymorphism instead.

Coupling measures dependency between modules; low coupling means less dependency. Cohesion measures how closely related the functions within a module are; high cohesion is better.

5fill in blank

hard

Fill all three blanks to complete the dictionary comprehension that filters principles by importance and formats keys.

Software Engineering

filtered = [1]: [2] for [3], importance in principles.items() if importance > 7

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

Aprinciples.keys()

Bimportance

Cprinciple.upper()

Dprinciple

Attempts:

3 left

💡 Hint

Common Mistakes

Using principles.keys() instead of iterating items.

Trying to uppercase keys without defining the variable.

This comprehension creates a new dictionary with keys as principle names and values as their importance, but only includes those with importance greater than 7.

Practice

1. Which software engineering principle encourages writing code that does one thing and does it well?

easy

A. Open/Closed Principle

B. Don't Repeat Yourself (DRY)

C. Single Responsibility Principle (SRP)

D. Keep It Simple, Stupid (KISS)

Solution

1. Step 1: Understand the principle names

   SRP means each module or class should have one responsibility or reason to change.

2. Step 2: Match the description to the principle

   Writing code that does one thing well matches SRP.

3. Final Answer:

   Single Responsibility Principle (SRP) -> Option C

4. Quick Check:

   One responsibility = SRP [OK]

Hint: One job per module means SRP [OK]

Common Mistakes:

• Confusing SRP with DRY which avoids repetition
• Thinking KISS means single responsibility
• Mixing Open/Closed with SRP

2. Which of the following is the correct description of the DRY principle?

easy

A. Avoid duplicating code or logic in multiple places

B. Keep code as simple as possible

C. Design software to be open for extension but closed for modification

D. Each class should have only one reason to change

Solution

1. Step 1: Recall DRY meaning

   DRY stands for "Don't Repeat Yourself", meaning avoid code duplication.

2. Step 2: Match option to DRY

   Avoid duplicating code or logic in multiple places says avoid duplicating code or logic, which matches DRY.

3. Final Answer:

   Avoid duplicating code or logic in multiple places -> Option A

4. Quick Check:

   DRY = no repetition [OK]

Hint: DRY means no repeated code [OK]

Common Mistakes:

• Confusing DRY with Open/Closed principle
• Mixing DRY with KISS which is about simplicity
• Thinking DRY means single responsibility

3. Consider this code snippet applying the KISS principle:

def calculate_area(radius):
    return 3.14 * radius * radius

area = calculate_area(5)
print(area)

What will be the output?

medium

A. 31.4

B. 78.5

C. Error due to missing import

D. None

Solution

1. Step 1: Calculate area using formula

   Area = π * radius² = 3.14 * 5 * 5 = 3.14 * 25 = 78.5

2. Step 2: Check code output

   The function returns 78.5 and print outputs it.

3. Final Answer:

   78.5 -> Option B

4. Quick Check:

   3.14 * 25 = 78.5 [OK]

Hint: Multiply π by radius squared for area [OK]

Common Mistakes:

• Using 2 * π * r (circumference) instead of area formula
• Expecting error due to missing math module (not needed here)
• Confusing output with None from missing return

4. Identify the error in this code violating the Open/Closed Principle:

class Shape:
    def area(self, shape_type, size):
        if shape_type == 'circle':
            return 3.14 * size * size
        elif shape_type == 'square':
            return size * size
        else:
            return 0

medium

A. The class is closed for modification

B. The method is open for extension without changes

C. The code uses inheritance properly

D. The area method uses conditional logic to handle multiple shapes

Solution

1. Step 1: Understand Open/Closed Principle

   It says software entities should be open for extension but closed for modification.

2. Step 2: Analyze the area method

   The method uses if-else to handle different shapes, so adding a new shape requires modifying this method.

3. Final Answer:

   The area method uses conditional logic to handle multiple shapes -> Option D

4. Quick Check:

   Conditional logic breaks Open/Closed [OK]

Hint: If-else for types breaks Open/Closed [OK]

Common Mistakes:

• Thinking inheritance is used properly here
• Believing the class is closed for modification
• Confusing open for extension with modifying code

5. You want to refactor this code to follow the Single Responsibility Principle (SRP):

class User:
    def __init__(self, name, email):
        self.name = name
        self.email = email
    def save_to_database(self):
        # code to save user data
        pass
    def send_welcome_email(self):
        # code to send email
        pass

What is the best way to apply SRP here?

hard

A. Move save_to_database to a separate DatabaseHandler class

B. Keep all methods in User class since they relate to user

C. Combine both methods into one method for simplicity

D. Remove send_welcome_email method entirely

Solution

1. Step 1: Understand SRP

   SRP says a class should have only one reason to change, so User should only hold user data.

2. Step 2: Identify responsibilities

   Saving to database and sending emails are separate concerns from user data storage.

3. Step 3: Refactor accordingly

   Move save_to_database to a DatabaseHandler class to separate concerns.

4. Final Answer:

   Move save_to_database to a separate DatabaseHandler class -> Option A

5. Quick Check:

   Separate responsibilities = SRP applied [OK]

Hint: One class, one reason to change means separate concerns [OK]

Common Mistakes:

• Keeping all methods in one class breaks SRP
• Combining methods increases complexity
• Removing functionality instead of refactoring