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Best Software Design Principles to Know in 2024

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24th Apr, 2024
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    Best Software Design Principles to Know in 2024

    As we head into 2024, let's take a moment to explore the heart and soul of software development - Design Principles. Think of it as the guiding light that will help you lead a path to creating a great digital product.

    In this blog, we'll talk about some of the coolest software design principles you need to know in 2024. From SOLID to DRY and beyond, these principles are like secret codes that unlock the power of coding magic.

    Whether you're a seasoned coder or a noob getting into the tech waters, understanding these principles will turbocharge your coding journey and help you in your goal to study Software Engineering. They'll help you write sleeker, smarter code and create software that's not just functional but downright awesome.

    So, grab your favorite beverage, settle into your coding chair, and let's embark on this journey into the exciting world of software design principles!

    What are Software Design Principles?

    Consider design principles in software engineering to be the core principles of perfect software. They act as our navigational compass in the enormous cosmos of programming. Software engineers use these concepts as a set of best practices and standards when they design and write code. They offer a road map for developing software that is efficient, scalable, and easy to maintain in addition to being functional. These guidelines form the basis for creating dependable, long-lasting software, from encouraging code reuse to keeping our code structured to reducing errors.

    Why are Software Design Principles Important?

    Software design principles are the secret sauce that ensures our codebase is not just functional but also robust, scalable, and maintained. They provide a roadmap for creating software that is both long-lasting and adaptive to changing user and stakeholder requirements. They also have a great impact in creating an efficient website.

    Furthermore, good software design principles increase the flexibility and adaptability of our code, allowing it to evolve gracefully as requirements change over time. This adaptability is critical in today's fast-paced technological environment.

    Finally, adherence to software design principles produces higher-quality software products that are easier to maintain, debug, and scale.

    Key Objectives of Software Design Principles

    Software design principles aim to achieve several key objectives in software development, KnowledgeHut's study Software Engineering dives deep into many such concepts of software engineering. Some These key objectives are as included below:

    • Enhance code readability and maintainability.
    • Promote code reuse and modularity.
    • Improve scalability and flexibility.
    • Minimize complexity and dependencies.
    • Create software that is easier to understand, modify, and extend.
    • Reduce development time and costs.
    • Build software that meets user needs effectively and efficiently.

    Best Software Design Principles for Software Engineering

    Diving right into the content, let's start with the best software design principles that every software engineer should know about.

    1. SOLID Principle

    SOLID software design principles are a widely recognized set of design principles that guide developers in creating software systems that are easy to maintain, scale, and optimize. These principles lay the foundation for writing code that is understandable, flexible, and can be extended with ease. By following the SOLID principles, developers can build a well-structured codebase that reduces the chances of bugs and simplifies the process of making changes.

    SOLID Principle
    mynoticeperiod

    SOLID is an acronym that represents five fundamental principles:

    • Single Responsibility Principle (SRP)
    • Open-Closed Principle (OCP)
    • Liskov Substitution Principle (LSP)
    • Interface Segregation Principle (ISP)
    • Dependency Inversion Principle (DIP)

    Now let's briefly explain other software design principles:

    A. Single Responsibility Principle (SRP)

    SRP states that a class should have only one reason to change, meaning it should have only one responsibility or job within the software system.

    Benefits:

    • Enhances code readability and maintainability.
    • Promotes code reuse and modularity.
    • Reduces the risk of unintended side effects when making changes.

    Guide to Apply:

    • Identify the distinct responsibilities within a class.
    • Refactor classes to ensure each one encapsulates only one responsibility.
    • Use cohesive naming conventions to indicate the purpose of each class.

    Example Code:

    class Employee:
def __init__(self, name, salary):
self.name = name
self.salary = salary
def calculate_salary(self):
return self.salary
class PayrollSystem:
def calculate_payroll(self, employees):
for employee in employees:
print(f'Payroll for: {employee.name} - {employee.calculate_salary()}')
class TaxCalculator:
def calculate_tax(self, employee):
return employee.calculate_salary() * 0.2

    By following the Single Responsibility Principle, you can design classes that are easier to understand, maintain, and modify.

    Single Responsibility Principle
    dev.to

    B. Open-Closed Principle (OCP)

    The Open-Closed design principles in software engineering state that software entities (classes, modules, functions, etc.) should be open for extension but closed for modification. This means that existing code should be closed for modification but open for extension through the addition of new functionality.

    Benefits:

    • Encourages code reuse and modularity.
    • Promotes maintainability and scalability.
    • Reduces the risk of introducing bugs when extending existing functionality.

    Guide to Apply:

    • Design classes and modules to be easily extendable without modifying existing code.
    • Utilize abstraction and inheritance to allow for extension without modification.
    • Implement interfaces or abstract classes to define contractually what should be extended.

    Example Code:

    from abc import ABC, abstractmethod
class Shape(ABC):
@abstractmethod
def area(self):
pass
class Rectangle(Shape):
def __init__(self, width, height):
self.width = width
self.height = height


def area(self):
return self.width * self.height
class Circle(Shape):
def __init__(self, radius):
self.radius = radius


def area(self):
return 3.14 * self.radius * self.radius

    Open Closed Principle
    dev.to

    C. Liskov Substitution Principle (LSP)

    The Liskov Substitution Principle states that objects of a superclass should be replaceable with objects of its subclasses without affecting the correctness of the program. In other words, a subclass should be able to substitute its superclass without altering the desired behavior of the program.

    Benefits:

    • Enhances code flexibility and extensibility.
    • Promotes code reuse and modularity.
    • Improves maintainability and scalability by allowing for easier addition of new subclasses.

    Guide to Apply:

    • Ensure that subclasses adhere to the same contract (interfaces, method signatures, etc.) as their superclass.
    • Avoid overriding or modifying the behavior of methods in ways that violate the expected behavior defined by the superclass.
    • Use polymorphism to enable interchangeable use of objects without impacting program behavior.

    Example Code:

    class Bird:
def fly(self):
print("Flying")
class Duck(Bird):
def quack(self):
print("Quack")
class Ostrich(Bird):
def fly(self):
raise NotImplementedError("Ostrich cannot fly")

    LSP
    dev.to

    D. Interface Segregation Principle (ISP)

    The Interface Segregation Principle states that clients should not be forced to depend on interfaces they do not use. Instead of having large, monolithic interfaces, ISP recommends breaking interfaces into smaller, specific ones, tailored to the needs of the clients.

    Benefits:

    • Promotes code modularity and reusability.
    • Reduces the risk of introducing bugs when implementing interfaces.
    • Improves code readability and maintainability by focusing on specific functionalities.

    Guide to Apply:

    • Identify distinct groups of behaviors or functionalities.
    • Define interfaces that cater to the specific needs of each group.
    • Implement classes that only depend on the interfaces relevant to their functionalities.

    Example Code

    from abc import ABC, abstractmethod
# Bad Example
class Worker(ABC):
@abstractmethod
def work(self):
pass


@abstractmethod
def eat(self):
pass
# Good Example
class Workable(ABC):
@abstractmethod
def work(self):
pass
class Eatable(ABC):
@abstractmethod
def eat(self):
pass
class Programmer(Workable):
def work(self):
print("Coding")
class Chef(Workable, Eatable):
def work(self):
print("Cooking")


def eat(self):
print("Eating")

    ISP
    dev.to

    E. Dependency Inversion Principle (DIP)

    The Dependency Inversion Principle suggests that high-level modules should not depend on low-level modules, but both should depend on abstractions. It promotes decoupling between modules by introducing interfaces or abstract classes that serve as contracts for dependencies.

    Benefits:

    • Facilitates loose coupling between modules, making the system more flexible and easier to maintain.
    • Promotes code reusability and modifiability by reducing the impact of changes in one module on others.
    • Enhances testability and scalability by allowing for easier substitution of dependencies during testing or system expansion.

    Guide to Apply:

    • Identify dependencies between modules and abstract them into interfaces or abstract classes.
    • Ensure that high-level modules depend on abstractions rather than concrete implementations.
    • Implement dependency injection to provide concrete implementations of dependencies to the dependent modules.

    Example Code:

    ```
from abc import ABC, abstractmethod
# Bad Example
class LightBulb:
def turn_on(self):
print("LightBulb: turned on")
class Switch:
def __init__(self):
self.light_bulb = LightBulb()
def turn_on(self):
self.light_bulb.turn_on()
# Good Example
class Switchable(ABC):
@abstractmethod
def turn_on(self):
pass
class LightBulb(Switchable):
def turn_on(self):
print("LightBulb: turned on")
class Switch:
def __init__(self, switchable: Switchable):
self.switchable = switchable
def turn_on(self):
self.switchable.turn_on()
# Usage
light_bulb = LightBulb()
switch = Switch(light_bulb)
switch.turn_on()
```

    DIP

    2. DRY (Don't Repeat Yourself)

    The DRY principle emphasizes that every piece of knowledge or logic should have a single, unambiguous representation within a system. It encourages code reuse and modularity by avoiding duplication of code, which reduces maintenance overhead and enhances readability.

    Benefits:

    • Enhances code maintainability by reducing the risk of inconsistencies and bugs introduced by duplicated code.
    • Promotes code readability and clarity by keeping code concise and focused on its purpose.
    • Improves development efficiency by facilitating easier modifications and updates across the codebase.

    Guide to Apply:

    • Identify duplicated code or logic across the codebase.
    • Refactor duplicated code into reusable functions, classes, or modules.
    • Utilize inheritance, composition, or abstraction to extract common functionalities and avoid repetition.

    Example Code:

    ```
# Bad Example
def calculate_area_of_rectangle(length, width):
return length * width
def calculate_area_of_square(side):
return side * side
# Good Example
def calculate_area(length, width=None):
if width is None:
return length * length # square
else:
return length * width # rectangle
# Usage
area_of_square = calculate_area(5)
area_of_rectangle = calculate_area(5, 3)
```

    3. Encapsulation Principle

    The Encapsulation Principle states that the internal workings of a class should be hidden from the outside world, and access to the class's data should only be possible through well-defined interfaces. It emphasizes data hiding and abstraction, allowing for better control over the class's behavior and reducing dependencies between components.

    Benefits:

    • Enhances code maintainability and scalability by reducing the impact of changes within the class on other parts of the system.
    • Improves code readability and understandability by encapsulating complex implementation details and exposing only essential interfaces.
    • Promotes reusability and modifiability by enforcing encapsulation boundaries, making it easier to refactor and extend the class.

    Guide to Apply:

    • Identify the data and behaviors that belong together within a class.
    • Encapsulate the data by making it private or protected and provide public methods to access and manipulate it.
    • Use access control modifiers (e.g., private, protected) to restrict direct access to class members from outside the class.

    Example Code:

    ```
# Bad Example
class Car:
def __init__(self, make, model, year):
self.make = make
self.model = model
self.year = year
car = Car("Toyota", "Camry", 2022)
car.year = 2023 # Direct access to class member
# Good Example
class Car:
def __init__(self, make, model, year):
self._make = make
self._model = model
self._year = year
def get_year(self):
return self._year
def set_year(self, year):
self._year = year
car = Car("Toyota", "Camry", 2022)
car.set_year(2023) # Access through public method
```

    4. Principle of Least Astonishment (PoLA)

    The Principle of Least Astonishment, also known as the Principle of Least Surprise, suggests that the behavior of a system or software component should align with users' expectations and intuition. It aims to minimize confusion and unexpected outcomes by adhering to common conventions and providing consistent and predictable behavior.

    Benefits:

    • Enhances user experience by reducing confusion and frustration.
    • Improves usability and learnability by aligning with users' mental models and expectations.
    • Increases user trust and confidence in the system or software product.

    Guide to Apply:

    • Understand the expectations and mental models of users.
    • Follow established conventions and standards in design and implementation.
    • Test user interfaces and interactions to ensure they align with users' expectations.

    Example: In a text editor application, pressing the "Save" button should save the current document to a file in a location that the user expects, such as the default documents folder, without prompting unexpected dialogs or actions.

    5. You Aren’t Gonna Need It (YAGNI)

     The You Aren’t Gonna Need It (YAGNI) principle advises against adding functionality or features to a system until they are actually needed. It discourages speculative or premature optimizations, extensions, or enhancements that may never be utilized.

    Benefits:

    • Reduces complexity and bloat in the codebase by avoiding unnecessary features.
    • Improves maintainability and clarity by keeping the code focused on its core functionality.
    • Increases development efficiency by prioritizing work on features essential to meeting current requirements.

    Guide to Apply:

    • Focus on implementing only the features and functionalities required to fulfill the current user requirements.
    • Avoid adding speculative or future-proofing features that may not be necessary in the near term.
    • Refactor or extend the codebase as needed when new requirements arise, rather than preemptively adding functionality.

    Example:

    ```
# Bad Example - Speculative Implementation
class ShoppingCart:
def __init__(self):
self.items = []
def add_item(self, item):
self.items.append(item)
def calculate_total(self):
total = 0
for item in self.items:
# Speculative feature: Apply discount for VIP customers
total += item.price * 0.9
return total
# Good Example - YAGNI Principle Applied
class ShoppingCart:
def __init__(self):
self.items = []
def add_item(self, item):
self.items.append(item)
def calculate_total(self):
total = 0
for item in self.items:
total += item.price
return total
# Usage
class Item:
def __init__(self, name, price):
self.name = name
self.price = price
# No need for speculative discount feature until it's actually required
# ShoppingCart remains simple and focused on current requirements
cart = ShoppingCart()
cart.add_item(Item("Product 1", 10))
cart.add_item(Item("Product 2", 20))
total_price = cart.calculate_total()
print("Total Price:", total_price)
```

    6. Keep It Simple, Stupid (KISS)

    The Keep It Simple, Stupid (KISS) principle advocates for simplicity in design and implementation. It suggests that systems should be kept as simple as possible, avoiding unnecessary complexity or over-engineering, to enhance understandability, maintainability, and reliability.

    Benefits:

    • Improves code readability and understandability.
    • Reduces the risk of bugs and errors by minimizing complexity.
    • Facilitates easier maintenance and troubleshooting.

    Guide to Apply:

    • Focus on achieving the desired functionality with the simplest design and implementation.
    • Break down complex problems into smaller, more manageable components.
    • Prioritize clarity and ease of understanding over unnecessary sophistication or cleverness.

    Example Code:

    ```
# Bad Example
def calculate_fibonacci(n):
if n <= 1:
return n
else:
return calculate_fibonacci(n-1) + calculate_fibonacci(n-2)
# Good Example
def calculate_fibonacci(n):
a, b = 0, 1
for _ in range(n):
a, b = b, a + b
return a
```

    KISS
    acronymat

    7. Problem Partitioning

    Problem partitioning is the process of breaking down a complex problem into smaller, more manageable subproblems. It involves identifying distinct components or tasks within the problem domain and decomposing them into separate units that can be tackled independently.

    Benefits:

    1. Facilitates easier problem-solving by breaking down complexity into smaller, more understandable parts.
    2. Enables parallel development and collaboration by dividing work among team members.
    3. Promotes code reusability and modularity by encapsulating functionality within well-defined components.

    Guide to Apply:

    1. Analyze the problem domain to identify distinct components or tasks.
    2. Decompose the problem into smaller subproblems based on functional or logical boundaries.
    3. Define interfaces or contracts between components to establish communication and interaction.
    4. Implement each subproblem as a separate module, class, or function, ensuring cohesion and minimal coupling.

    Example Code:

    ```
# Problem: Calculate the total price of items in a shopping cart.
# Subproblem 1: Calculate the price of an individual item.
def calculate_item_price(item):
return item['quantity'] * item['price']
# Subproblem 2: Calculate the total price of items in the shopping cart.
def calculate_total_price(cart):
total_price = 0
for item in cart:
total_price += calculate_item_price(item)
return total_price
# Example usage
cart = [{'name': 'Apple', 'quantity': 2, 'price': 1.50},
{'name': 'Banana', 'quantity': 3, 'price': 0.75}]
total_price = calculate_total_price(cart)
print("Total price:", total_price)
```

    In this example, the problem of calculating the total price of items in a shopping cart is partitioned into two subproblems: calculating the price of an individual item and calculating the total price of all items in the cart. Each subproblem is addressed by a separate function, promoting code modularity and maintainability.

    8. Strategy of Design

    The strategy of design refers to the approach or methodology used to plan, organize, and implement the design process for creating a product or system. It involves defining the overarching principles, methods, and techniques that guide the design efforts from conception to realization.

    Benefits:

    1. Provides a structured framework for approaching design challenges.
    2. Ensures consistency and coherence in design decisions and outcomes.
    3. Facilitates collaboration and communication among team members involved in the design process.
    4. Helps manage complexity and uncertainty by breaking down the design process into manageable steps.

    Guide to Apply:

    1. Define Objectives: Clearly articulate the goals and objectives of the design project, including user needs, technical requirements, and business objectives.
    2. Research and Analysis: Conduct research and analysis to understand the problem domain, user behaviors, market trends, and technical constraints.
    3. Generate Ideas: Brainstorm and explore potential design solutions, considering various perspectives and alternative approaches.
    4. Prototype and Iterate: Develop prototypes or mockups to visualize and evaluate design concepts and iterate based on feedback and testing.
    5. Refine and Finalize: Refine the chosen design solution based on feedback and insights gathered during prototyping and finalize the design for implementation.
    6. Implementation and Evaluation: Implement the design solution, monitor its performance and usability, and gather feedback for continuous improvement.

    Example:

    A software development team follows an iterative design strategy, starting with a thorough understanding of user needs and technical requirements. They conduct user research, create personas, and develop wireframes and prototypes to validate design concepts. Through iterative cycles of feedback and refinement, they gradually evolve the design solution, ensuring alignment with user expectations and project goals. Finally, they implement the finalized design and conduct usability testing to evaluate its effectiveness and make further improvements.

    Strategies to Communicate Design Principles Effectively

    • Documentation: Creating comprehensive documentation that outlines design principles, their rationale, and best practices ensures that developers have a reference point for understanding and applying them in their work.
    • Training: Conducting regular training sessions or workshops to educate team members about design principles and how they can be implemented fosters a culture of understanding and adherence within the team.
    • Code Reviews: Incorporating design principle discussions into code review processes encourages peer feedback and ensures that code aligns with established principles before it is merged into the codebase.
    • Regular Discussions: Hosting regular team discussions or meetings dedicated to discussing design principles, sharing insights, and addressing any questions or concerns helps keep the principles top of mind and encourages collaboration and knowledge sharing.
    • Real-World Examples: Providing real-world examples or case studies that demonstrate the application of design principles in practical scenarios helps contextualize their importance and illustrates their impact on software quality and maintainability.
    • Leadership Commitment: Ensuring leadership commitment to prioritizing and upholding design principles sets a clear expectation for their importance within the organization and encourages buy-in from team members.
    • Adapt and Evolve: Recognizing that design principles may need to adapt and evolve over time to meet changing requirements and technological advancements fosters a culture of continuous improvement and ensures that principles remain relevant and effective in guiding software development practices.

    Conclusion

    In wrapping up, think of software design principles as the trusted compass guiding developers through the wild terrain of coding. They're like the seasoned trail markers, showing the way to creating software that's not just functional, but truly exceptional. By adhering to concepts like SOLID, DRY, and KISS, we tend to create better software and therefore craft better digital Products that stand the test of time, please check Web Development crash course to understand how. These principles aren't just rules; they're the foundational principles that have been penned down by developers who've learned that simplicity, clarity, and adaptability are the keys to success in the ever-changing world of software engineering. So, as we continue our journey in this exciting field, let's remember to keep these principles in mind, while they help us pave the way for the future of technology.

    Frequently Asked Questions (FAQs)

    1. How do software design principles differ from coding standards?

    Software design principles and coding standards are two distinct aspects of software development. Design principles focus on high-level guidelines for structuring and organizing software components to achieve desired qualities like maintainability and extensibility. While design principles guide the overall architecture and design decisions, coding standards ensure uniformity and readability in the codebase.

    2. What are some common software design principles used in the industry?

    The common software design principles used in the industry 

    • SOLID Principles 
    • DRY (Don't Repeat Yourself): This principle promotes code reuse and reducing redundancy by extracting common functionality into reusable components. 
    • KISS (Keep It Simple, Stupid) 
    • YAGNI (You Ain't Gonna Need It) 
    • Encapsulation Principle 
    3. How does the "open/closed principle" contribute to maintainable software?

    The "open/closed principle" contributes to maintainable software by promoting modularity and extensibility. According to the principle, software entities should be open for extension but closed for modification. This means that when new functionality needs to be added, it should be done through extension rather than modifying existing code.

    4. Do I need to be an expert to use software design principles?

    No, you do not need to be an expert to use software design principles. These principles are guidelines that can be applied by developers at various skill levels to improve the quality and maintainability of their software.

    Profile

    Nikhilesh Pandey

    Author

    "Experienced Lead Developer oriented towards problem-solving and analyzing impacts, both technically and functionally, Enjoy's working with web technologies with a strong focus on quality code and robust system architecture."

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