Design Patterns Cheat Sheet - When to Use Which Design Pattern?

In system design, selecting the right design pattern is related to choosing the right tool for the job. It's essential for crafting scalable, maintainable, and efficient systems. Yet, among a lot of options, the decision can be difficult. This Design Patterns Cheat Sheet serves as a guide, helping you on the path toward optimal design pattern selection. Simplifying complex concepts into easy insights empowers engineers to navigate design patterns confidently.

What are Design Patterns?

Design patterns are reusable solutions to common problems encountered during software design and development. They represent established best practices for structuring code to address specific challenges in a standardized and efficient manner.

• By following design patterns, developers can streamline the development process, enhance code clarity, and facilitate communication among team members.
• Examples of design patterns include Singleton, Factory, Observer, Strategy, and many others, each helps to address distinct sets of problems.

When to Use Which Design Pattern?

Before we select a pattern, we must identify and understand the problem we have encountered, and based on that we can choose which sub-category of design pattern we can go for, Let us see in this Design Patterns Cheat Sheet, that in which scenario to choose which design pattern, that can effectively solve our problem:

When to Choose Creational Design Patterns?

According to this Design Patterns Cheat Sheet, choose creational design patterns when object creation is complex, involves multiple steps, or requires specific initialization. They're useful for promoting reusability, encapsulating creation logic, and decoupling client code from classes it instantiates.

• Creational patterns enhance flexibility, making it easier to change or extend object creation methods at runtime.
• Common patterns include Singleton, Factory Method, Abstract Factory, Builder, and Prototype. Use them to improve maintainability, readability, and scalability of your codebase.

We must choose Creational Design Patterns when the Problem is related to Object Creation.

1. Singleton: Makes sure there is just one instance.
2. Factory Method: Assigns subclasses the task of instantiating objects.
3. Abstract Factory: Constructs related object families without defining their concrete classes.
4. Prototype: Clones objects to provide a template example.
5. Builder: Helps in building the complex objects step by step.

When to Choose Structural Design Patterns?

According to this Design Patterns Cheat Sheet, choose structural design patterns when you need to compose objects and classes into larger structures while keeping them flexible and efficient. These patterns are useful for clarifying relationships between classes, managing object hierarchies, and altering interfaces without affecting clients.

• Structural patterns promote code reuse, simplify system design, and enhance scalability.
• They're beneficial when dealing with complex systems, integration of new components, or refactoring existing codebases.

We must choose Structural Design Patterns when the Problem is related to Object Assembly.

1. Adapter: Acts as a bridge between two incompatible interfaces
2. Bridge: Separates the abstraction from the implementation.
3. Composite: Handles single and composite objects equally.
4. Decorator: Adds behaviors to objects dynamically.
5. Facade: Helps in Simplifying the complex system interfaces.
6. Flyweight: Shares common parts of state between multiple objects to reduce memory.
7. Proxy: Controls the access to an object.

When to Choose Behavioral Design Patterns?

According to this Design Patterns Cheat Sheet, choose behavioral design patterns when you need to manage algorithms, communication, or responsibilities between objects. They're useful for encapsulating behavior that varies and promoting loose coupling between objects.

• Behavioral patterns facilitate code reuse, flexibility, and maintainability by defining how objects interact and communicate.
• Use them to address scenarios like handling complex workflows, managing state transitions, or implementing communication between objects.

We must choose Behavioral Design Patterns when the Problem is related to Object Interactions.

1. Observer: Observes and notifies changes in multiple objects.
2. Strategy: Encapsulates the interchangeable algorithms.
3. Command: Encapsulates requests as objects for decoupled execution.
4. State: It Changes the behavior of object with internal state.
5. Visitor: It separates algorithms from objects.
6. Memento: Pattern to manage object state and actions.
7. Iterator: It Sequentially accesses the elements of a collection.
8. Mediator: Central controller managing communication between objects.
9. Chain of Responsibility: Pass request through handlers until one handles it.
10. Template Method: Defines the skeleton of an algorithm.

Importance of Choosing the Right Design Pattern

According to this Design Patterns Cheat Sheet, choosing the right design pattern is crucial due to:

• Scalability: Ensures the architecture can accommodate growth without excessive restructuring.
• Flexibility: Enables easy adaptation to changing requirements and future enhancements.
• Maintainability: Facilitates code readability and comprehension, easing maintenance tasks.
• Reusability: Promotes reuse of proven solutions, saving development time and effort.
• Performance: Optimizes code execution and resource utilization for efficient operation.
• Reducing Errors: Helps avoid common pitfalls and design flaws, leading to fewer bugs and issues.

Conclusion

With the help of this Design Patterns Cheat Sheet, selecting the appropriate design pattern is crucial for effective problem-solving in software development. By understanding the characteristics of different design patterns and analyzing the specific requirements and constraints of the problem at hand, developers can make informed decisions that lead to more maintainable, scalable, and efficient solutions.

Moreover, the choice of design pattern can significantly impact the readability, flexibility, and extensibility of the codebase. It allows developers to leverage proven solutions to common design problems, reducing the chances of errors and promoting code reusability.