What is Design Pattern?

Introduction

Design patterns are tried-and-true fixes for typical issues with software design that developers run across during the creation process. They offer a methodical way to deal with design problems, improving the reuse, adaptability, and maintainability of the code. Developers can use tried-and-true methods and concepts to build reliable and effective software systems by adhering to different types of design patterns in software engineering.

Overview

The three basic categories of design patterns are creational, structural, and behavioral. Object formation is the primary emphasis of creational patterns; object composition and connections are the primary concerns of structural patterns; and the interaction and delegating of tasks between objects are the primary concerns of behavioral patterns.

Classification of Design Patterns

Design patterns have been classified into the following:

Creational Design Patterns

Creational design patterns are concerned with object creation mechanisms. They provide ways to create objects while decoupling the system from the specific classes it uses for object creation. Some common creational design patterns include:

• Singleton: A singleton makes sure that just one instance of a class is produced and grants that instance access to the whole world. When you only want one object to be able to instantiate a class, this approach might be helpful.
• Factory Method: When using the factory design pattern method, subclasses can choose which class to instantiate while still having an interface for producing objects defined. This pattern promotes loose coupling between the creator and the objects it creates.
• Abstract Factory: Provides an interface for creating families of related or dependent objects without specifying their concrete classes. This pattern enables the creation of items that are compatible with one another and guarantees the usage of a family of connected objects.
• Builder: By separating the creation of a complicated object's construction from its representation, it is possible to generate many representations using the same construction method. When you want to build an item step-by-step and have control over the process, this pattern might be helpful.

Structural Design Patterns

Structural design patterns deal with the composition of classes and objects to form larger structures and provide new functionality. They focus on how objects and classes can be combined to form flexible and efficient structures. Some common structural types of design pattern in software engineering include:

• Bridge: Decouples an abstraction from its implementation, allowing them to vary independently. This pattern is useful when you want to avoid a permanent binding between an abstraction and its implementation.
• Composite: Composes objects into tree structures to represent part-whole hierarchies. It lets clients treat individual objects and compositions of objects uniformly.
• Decorator: Dynamically adds new behavior to an object by wrapping it in an object of a decorator class. This pattern provides a flexible alternative to subclassing for extending functionality.
• Facade: Provides a simplified interface to a complex system of classes, serving as a higher-level interface that makes the subsystem easier to use.
• Flyweight: Shares objects to support large numbers of fine-grained objects efficiently. It reduces memory usage by sharing common data between multiple objects.
• Proxy: Provides a placeholder or surrogate for another object to control access to it. This pattern is useful when you want to add additional functionality or control access to an object.

Behavioural Design Patterns

Behavioral design patterns focus on the interaction and communication between objects. They capture patterns of communication and help in organizing the responsibilities between objects. Some common behavioral types of design pattern in C++ include:

• Observer: Defines a one-to-many dependency between objects so that when one object changes state, all its dependents are notified and updated automatically.
• Strategy: Encapsulates alternative algorithms in separate classes, allowing clients to choose different algorithms at runtime. This pattern enables the selection of an algorithm at runtime without tightly coupling the client to the algorithm implementation.
• Command: Encapsulates a request as an object, allowing you to parameterize clients with requests, queue or log requests, and support undoable operations.
• Iterator: Provides a way to access elements of an aggregate object sequentially without exposing its underlying representation.
• State: Allows an object to alter its behavior when its internal state changes. It encapsulates state-specific behavior into separate classes and allows an object to change its behavior dynamically at runtime.
• Template Method: Defines the skeleton of an algorithm in a base class, with subclasses providing implementations of certain steps. This pattern allows subclasses to redefine certain steps of an algorithm without changing its structure.
• Visitor: Separates an algorithm from the objects it operates on. It allows adding new operations to existing object structures without modifying the structures themselves.
• Interpreter: Defines a representation of grammar and an interpreter to interpret sentences in the language defined by the grammar. This pattern is useful when you need to interpret sentences in a language and want to avoid creating a separate class for each rule in the grammar.

Examples of Design Patterns

Following are the design patterns examples:

• Singleton Design pattern: A design pattern known as the singleton guarantees that only one instance of a class is produced and gives that instance a global access point. It is frequently employed when there has to be a single point of access to a shared resource or when system-wide coordination is required. For instance, the Singleton pattern may be used to design a logging system in a multi-threaded programme to guarantee that all threads write to the same log file.
• Design Pattern for Observers: Multiple observers are automatically alerted when the state of the subject (or observed object) changes, according to the Observer pattern, which creates a one-to-many dependence between objects. This pattern is useful when there is a need for loose coupling between objects and for maintaining consistency between dependent objects. For instance, in a weather application, the weather station can notify multiple displays or devices to update their information whenever the weather conditions change.

Advantages of Design Patterns

Below listed are the advantages of design patterns:

1. Reusability: Design patterns provide reusable solutions to common problems, allowing developers to save time and effort by leveraging existing proven solutions rather than reinventing the wheel.
2. Flexibility: Patterns promote flexible designs that can adapt and evolve over time. They help separate concerns, making it easier to modify and extend specific parts of a system without affecting the entire structure.
3. Maintainability: By following design patterns, code becomes more organized and easier to maintain. Patterns provide a clear structure and standard practices, making it simpler to understand, debug, and enhance the software.
4. Scalability: Design patterns encourage modular designs, making it easier to scale and add new features to the system. They facilitate the management of complexity and support the growth of the application as requirements change.
5. Collaboration: Design patterns provide a common language and set of practices that facilitate communication and collaboration among developers. They enable teams to work together more efficiently, ensuring a consistent and coherent approach to software design.

Disadvantages of Design Patterns

Below listed are the disadvantages of design patterns:

1. Complexity: Some design patterns can introduce additional complexity to the codebase, especially if not implemented correctly. Overusing patterns or applying them in inappropriate situations can make the code harder to understand and maintain.
2. Learning Curve: Design patterns require knowledge and understanding to use effectively. Developers need to be familiar with different patterns and their implementations, which may require time and effort to learn and apply correctly.
3. Over-Engineering: Misusing or overusing various types of design patterns in Java can lead to over-engineering, where the code becomes overly complex and bloated. It's essential to strike a balance and apply patterns judiciously based on the specific requirements of the system.
4. Performance Overhead: Some design patterns, while providing flexibility and modularity, may introduce performance overhead. It's crucial to carefully consider the performance implications of using certain patterns, especially in performance-critical systems.
5. Design Rigidity: In some cases, many types of design patterns in C# can make the code more rigid and less adaptable to change. Over-reliance on certain patterns may hinder the system's ability to evolve and adapt to new requirements.

Conclusion

Powerful techniques called design patterns offer tried-and-true answers to typical design issues in software development. They have several advantages, including collaboration, scalability, flexibility, maintainability, and code reuse. Developers may build effective, well-structured, and simple-to-understand, alter, and maintain software systems by adhering to design patterns.

However, it's crucial to utilize design patterns sparingly and take into account the particular requirements and limitations of the system. Overuse or improper use of design patterns can result in obtrusive complexity, excessive engineering, and decreased flexibility. It's crucial to maintain equilibrium and use patterns where they add the greatest value.

FAQs

1. Are design patterns specific to a particular programming language?

No, design patterns are not tied to any specific programming language. They are principles and concepts that can be applied across various programming languages and paradigms.

2. Can I create my own design patterns?

Yes, it is possible to create your own design patterns. However, it's important to ensure that they solve a recurring problem and provide a reusable and effective solution. It's recommended to study and understand existing design patterns before creating your own.

3. Are design patterns only applicable to large-scale projects?

No, design patterns can be beneficial in projects of all sizes. While some patterns may be more commonly used in large-scale projects, many patterns can be applied to smaller projects as well. The decision to use design patterns should be based on the complexity and specific needs of the project.

4. Are design patterns a substitute for good coding practices?

No, design patterns should not be seen as a substitute for good coding practices. They complement good coding practices by providing higher-level solutions to design problems. It's important to follow best coding practices alongside design patterns for optimal software development.

5. How can I learn and apply design patterns effectively?

To learn and apply design patterns effectively, it's recommended to study the different types of design pattern, understand their concepts and purposes, and practice implementing them in real-world scenarios. Reading books, and tutorials, and studying code examples can be helpful in gaining a deeper understanding of design patterns. Additionally, collaborating with experienced developers and participating in coding communities can provide valuable insights and feedback on your design pattern implementations.