Design patterns are essential tools in software development, offering reusable solutions to common problems. They help create more modular, flexible, and maintainable code by providing standardized approaches to design challenges.
This topic explores the three main categories of design patterns: creational, structural, and behavioral. It delves into specific patterns within each category, discussing their purposes, benefits, and implementation considerations. Understanding these patterns equips developers with powerful techniques for crafting robust software systems.
Categories of design patterns
Design patterns are reusable solutions to commonly occurring problems in software design
They provide a standardized approach to solving design problems, making code more modular, flexible, and maintainable
Design patterns are categorized into three main groups: creational, structural, and
Creational design patterns
Creational design patterns focus on object creation mechanisms, trying to create objects in a manner suitable to the situation
These patterns provide a way to create objects while hiding the creation logic, rather than instantiating objects directly using the
new
operator
help in achieving loose coupling between classes and objects, making the system more flexible and easier to maintain
Abstract factory pattern
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Provides an interface for creating families of related or dependent objects without specifying their concrete classes
Allows the creation of object families without exposing the underlying implementation details
Promotes loose coupling by eliminating the need to bind application-specific classes into the code
Builder pattern
Separates the construction of a complex object from its representation, allowing the same construction process to create different representations
Provides a step-by-step approach to construct complex objects, making the code more readable and maintainable
Useful when dealing with objects that have many optional or required parameters (e.g., building a custom car with various options)
Factory method pattern
Defines an interface for creating an object, but lets subclasses decide which class to instantiate
Allows a class to defer instantiation to subclasses, providing a way to encapsulate object creation
Promotes loose coupling by eliminating the need to bind application-specific classes into the code
Prototype pattern
Specifies the kinds of objects to create using a prototypical instance, and creates new objects by copying this
Allows the cloning of objects without coupling the code to their specific classes
Useful when creating new objects that are similar to existing objects, avoiding the cost of creating objects from scratch
Singleton pattern
Ensures that a class has only one instance and provides a global point of access to it
Useful when exactly one object is needed to coordinate actions across the system (e.g., a database connection pool)
Provides a way to control access to shared resources, such as a file or a database
Structural design patterns
Structural design patterns focus on the composition of classes and objects to form larger structures
These patterns help in creating relationships between entities, making the system more flexible and efficient
are concerned with how classes and objects are composed to form larger structures
Adapter pattern
Converts the interface of a class into another interface that clients expect, allowing classes with incompatible interfaces to work together
Useful when integrating existing classes or third-party libraries that have incompatible interfaces
Promotes by allowing existing classes to be used in new contexts without modifying their code
Bridge pattern
Decouples an from its implementation, allowing them to vary independently
Useful when dealing with multiple dimensions of abstraction and implementation (e.g., different shapes and colors)
Promotes flexibility by allowing the addition of new abstractions and implementations without affecting existing code
Composite pattern
Composes objects into tree structures to represent part-whole hierarchies, allowing clients to treat individual objects and compositions of objects uniformly
Useful when dealing with hierarchical structures (e.g., a file system with directories and files)
Simplifies client code by providing a uniform interface for both individual objects and compositions
Decorator pattern
Attaches additional responsibilities to an object dynamically, providing a flexible alternative to subclassing for extending functionality
Useful when adding behavior to individual objects without affecting the behavior of other objects from the same class
Promotes flexibility by allowing the addition or removal of responsibilities at runtime
Facade pattern
Provides a unified interface to a set of interfaces in a subsystem, defining a higher-level interface that makes the subsystem easier to use
Useful when dealing with complex subsystems that have many classes and interfaces
Simplifies client code by providing a single entry point to the subsystem, hiding its complexity
Flyweight pattern
Uses sharing to support large numbers of fine-grained objects efficiently, minimizing memory usage
Useful when dealing with a large number of objects that have similar or identical (e.g., characters in a text editor)
Promotes efficiency by sharing common state between objects instead of storing it in each object
Proxy pattern
Provides a surrogate or placeholder for another object to control access to it
Useful when creating expensive objects on demand (lazy initialization), controlling access to sensitive objects, or adding additional behavior to an object
Promotes flexibility by allowing the addition of new behavior without modifying the original object
Behavioral design patterns
Behavioral design patterns focus on the communication and interaction between objects and classes
These patterns help in defining the communication between objects, making the system more flexible and maintainable
Behavioral patterns are concerned with algorithms and the assignment of responsibilities between objects
Chain of responsibility pattern
Avoids coupling the sender of a request to its receiver by giving more than one object a chance to handle the request, passing the request along the chain until an object handles it
Useful when dealing with a series of handlers that can process a request (e.g., a logging system with different log levels)
Promotes loose coupling by allowing the addition or removal of handlers without affecting the client code
Command pattern
Encapsulates a request as an object, thereby letting you parameterize clients with different requests, queue or log requests, and support undoable operations
Useful when dealing with operations that need to be executed at a later time or in a different context (e.g., a undo/redo system)
Promotes loose coupling by separating the object that invokes the operation from the one that knows how to perform it
Interpreter pattern
Defines a representation for a grammar and an that uses the representation to interpret sentences in the language
Useful when dealing with a simple language or query that needs to be interpreted (e.g., a SQL query parser)
Promotes flexibility by allowing the addition of new expressions or interpreters without modifying existing code
Iterator pattern
Provides a way to access the elements of an aggregate object sequentially without exposing its underlying representation
Useful when dealing with collections of objects that need to be traversed in a uniform way (e.g., a list or a tree)
Promotes loose coupling by separating the traversal algorithm from the collection being traversed
Mediator pattern
Defines an object that encapsulates how a set of objects interact, promoting loose coupling by keeping objects from referring to each other explicitly
Useful when dealing with a group of objects that communicate in a complex way (e.g., a chat room application)
Simplifies object communication by providing a central point of control, reducing the dependencies between objects
Memento pattern
Captures and externalizes an object's internal state so that the object can be restored to this state later, without violating
Useful when dealing with objects that need to be saved and restored to a previous state (e.g., a text editor with undo/redo functionality)
Promotes encapsulation by keeping the state of an object private while allowing it to be saved and restored
Observer pattern
Defines a one-to-many dependency between objects so that when one object changes state, all its dependents are notified and updated automatically
Useful when dealing with objects that need to be notified of changes in other objects (e.g., a stock market application)
Promotes loose coupling by allowing objects to interact without knowing each other's identities
State pattern
Allows an object to alter its behavior when its internal state changes, appearing as if the object changed its class
Useful when dealing with objects that have different behavior based on their internal state (e.g., a traffic light system)
Promotes flexibility by allowing the addition of new states without modifying existing code
Strategy pattern
Defines a family of algorithms, encapsulates each one, and makes them interchangeable, letting the algorithm vary independently from clients that use it
Useful when dealing with a family of related algorithms that need to be selected at runtime (e.g., different sorting algorithms)
Promotes flexibility by allowing the addition of new algorithms without modifying existing code
Template method pattern
Defines the skeleton of an algorithm in a method, deferring some steps to subclasses, allowing subclasses to redefine certain steps of an algorithm without changing its structure
Useful when dealing with algorithms that have similar steps but vary in some specific parts (e.g., a data processing pipeline)
Promotes code reuse by defining a common structure for a family of algorithms
Visitor pattern
Represents an operation to be performed on the elements of an object structure, letting you define a new operation without changing the classes of the elements on which it operates
Useful when dealing with an object structure that needs to perform operations on its elements without modifying their classes (e.g., a compiler that generates code for different target platforms)
Promotes flexibility by allowing the addition of new operations without modifying the object structure or its elements
Benefits of design patterns
Design patterns offer several benefits that can improve the quality, , and flexibility of software systems
By using proven solutions to common design problems, developers can save time and effort while creating more robust and efficient code
Design patterns provide a common vocabulary for developers, making it easier to communicate and collaborate on design decisions
Reusability and flexibility
Design patterns promote code reuse by providing generic solutions that can be adapted to specific contexts
By encapsulating common design structures and behaviors, patterns allow developers to create modular and flexible code that can be easily modified or extended
Patterns help in creating loosely coupled systems, making it easier to change or replace components without affecting the rest of the system
Improved code readability
Design patterns provide a standardized way of structuring code, making it easier for developers to understand and navigate the codebase
By using well-known patterns, developers can quickly grasp the purpose and functionality of different parts of the system
Patterns help in creating self-documenting code, reducing the need for extensive comments or documentation
Faster development process
By providing proven solutions to common design problems, patterns can help developers avoid reinventing the wheel and focus on solving domain-specific problems
Patterns offer a starting point for designing and implementing complex systems, reducing the time and effort required to create a working solution
By using patterns, developers can leverage the collective experience and knowledge of the software development community
Standardized solutions to common problems
Design patterns capture the best practices and expertise of experienced developers, providing standardized solutions to recurring design problems
By using patterns, developers can ensure that their code adheres to industry standards and follows established design principles
Patterns help in creating consistent and maintainable code across different projects and teams
Drawbacks of design patterns
While design patterns offer many benefits, they also have some potential drawbacks that developers should be aware of
Overusing or misusing patterns can lead to unnecessary complexity, performance overhead, and maintainability issues
It's important to carefully consider the specific needs and constraints of a project before applying design patterns
Increased complexity for simple problems
Applying design patterns to simple problems can lead to overengineering and unnecessary complexity
In some cases, a straightforward solution may be more appropriate and easier to maintain than a pattern-based approach
Developers should carefully evaluate whether a pattern is truly needed for a given problem or if a simpler solution would suffice
Overuse leading to over-engineering
Overusing design patterns can result in a system that is more complex than necessary, making it harder to understand, modify, and maintain
Developers may be tempted to use patterns even when they are not needed, leading to a bloated and over-engineered codebase
It's important to strike a balance between using patterns when appropriate and keeping the code simple and focused on solving the problem at hand
Learning curve for team members
Design patterns can introduce a learning curve for team members who are not familiar with them
Developers may need to invest time in understanding the purpose, structure, and implementation of different patterns
This learning curve can slow down the development process initially, especially if the team is not experienced in using patterns
Selecting appropriate design patterns
Choosing the right design pattern for a given problem is crucial for creating an effective and maintainable solution
Developers should carefully consider the specific requirements, constraints, and context of the problem before selecting a pattern
Several factors should be taken into account when evaluating the suitability of a pattern for a particular situation
Identifying the problem domain
The first step in selecting an appropriate design pattern is to clearly identify the problem domain and the specific design challenges that need to be addressed
Developers should analyze the requirements, constraints, and goals of the system to determine which aspects of the design could benefit from the use of patterns
By understanding the problem domain, developers can narrow down the set of patterns that are most relevant and applicable to the situation
Considering scalability and maintainability
When selecting a design pattern, it's important to consider the and maintainability requirements of the system
Developers should evaluate how the chosen pattern will impact the system's ability to handle growth, changes, and evolution over time
Patterns that promote loose coupling, modularity, and flexibility are often better suited for systems that need to be scalable and maintainable
Evaluating trade-offs and alternatives
Design patterns often involve trade-offs between different quality attributes, such as performance, simplicity, and flexibility
Developers should carefully evaluate these trade-offs and consider alternative solutions that may be more suitable for the specific context
In some cases, a custom solution or a combination of patterns may be more appropriate than a single pattern
Implementing design patterns
Once an appropriate design pattern has been selected, the next step is to implement it in the codebase
Implementing design patterns requires a good understanding of the pattern's structure, participants, and collaborations
Developers should follow best practices and guidelines to ensure that the pattern is implemented correctly and effectively
Language-specific considerations
The implementation of design patterns can vary depending on the programming language and its features
Developers should be aware of the language-specific constructs, idioms, and libraries that can facilitate the implementation of patterns
Some languages may have built-in support for certain patterns (e.g., the
[Iterator](https://www.fiveableKeyTerm:iterator)
interface in Java), while others may require more manual implementation
Best practices and guidelines
When implementing design patterns, developers should follow established best practices and guidelines to ensure code quality and consistency
This includes adhering to naming conventions, using appropriate abstractions and interfaces, and maintaining a clear separation of concerns
Developers should also strive to keep the implementation simple, focused, and aligned with the pattern's intent
Testing and debugging strategies
Implementing design patterns introduces additional complexity and indirection into the codebase, which can make testing and debugging more challenging
Developers should adopt appropriate testing and debugging strategies to ensure that the pattern is implemented correctly and behaves as expected
This may involve creating unit tests for individual components, integration tests for the overall pattern, and using debugging tools to trace the flow of execution
Design patterns in real-world applications
Design patterns have been successfully applied in a wide range of real-world applications across different domains
Studying examples of successful pattern implementations can provide valuable insights and inspiration for developers
Analyzing case studies and lessons learned from real-world projects can help developers avoid common pitfalls and adopt best practices
Examples across different domains
Design patterns have been used in various domains, such as web development, mobile apps, enterprise systems, and embedded software
For example, the Model-View-Controller (MVC) pattern is commonly used in web frameworks (e.g., Ruby on Rails, ASP.NET MVC) to separate the concerns of data, presentation, and user interaction
The pattern is often used in event-driven systems (e.g., user interfaces, messaging systems) to decouple the components and enable flexible communication
Case studies of successful implementations
Studying case studies of successful pattern implementations can provide valuable insights into how patterns can be applied effectively in real-world contexts
For example, the Apache Hadoop project uses the pattern to add functionality to its file system API without modifying the core classes
The Eclipse IDE uses the pattern to implement its undo/redo functionality, allowing users to easily revert or repeat actions
Lessons learned and pitfalls to avoid
Analyzing the lessons learned and pitfalls encountered in real-world projects can help developers avoid common mistakes and adopt best practices
For example, overusing the pattern can lead to tight coupling and make testing and maintenance more difficult
Misapplying the pattern can result in a complex and hard-to-understand codebase if the object structure is not stable or well-defined
By learning from the experiences of others, developers can make informed decisions and improve their own pattern implementations
Key Terms to Review (42)
Abstract Factory: An abstract factory is a design pattern that provides an interface for creating families of related or dependent objects without specifying their concrete classes. This pattern allows clients to work with multiple types of products, ensuring that the products created are compatible with each other. By decoupling the creation of objects from their usage, the abstract factory promotes flexibility and scalability in software design.
Abstraction: Abstraction is the process of simplifying complex systems by focusing on the essential characteristics while ignoring irrelevant details. In design and software development, this allows for creating models or representations that facilitate understanding, communication, and problem-solving without getting bogged down by complexities.
Adapter: An adapter is a design pattern that acts as a bridge between two incompatible interfaces, allowing them to work together seamlessly. By converting the interface of one class into an interface that another class expects, adapters enable classes to communicate that otherwise couldn’t due to incompatible interfaces. This pattern is particularly useful in scenarios where existing code cannot be modified but needs to integrate with new systems or components.
Agile: Agile is a flexible and iterative approach to project management and software development that emphasizes collaboration, customer feedback, and rapid delivery of functional products. This method promotes adaptive planning and encourages evolutionary development, which allows teams to respond quickly to changes in requirements and market conditions.
Behavioral patterns: Behavioral patterns are recurring solutions to common problems in software design that focus on the interaction and responsibilities of objects. They help define how objects communicate and collaborate, making systems more manageable and scalable. By following these patterns, designers can create flexible and reusable code that can adapt to changing requirements over time.
Bridge: In design patterns, a bridge is a structural pattern that separates an abstraction from its implementation, allowing them to evolve independently. This approach promotes flexibility and scalability, as it enables designers and developers to change the implementation without affecting the abstraction and vice versa. A bridge is particularly useful when both the abstraction and the implementation can vary significantly.
Builder: A builder is a creational design pattern that focuses on constructing complex objects step by step. It provides a flexible solution for creating objects by separating the construction process from the representation, allowing the same construction process to create different representations. This pattern is especially useful when an object requires numerous parameters or configurations, ensuring that the creation process remains manageable and readable.
Chain of Responsibility: Chain of Responsibility is a behavioral design pattern that allows a request to be passed along a chain of handlers until one of them handles the request. This pattern promotes loose coupling by allowing multiple objects to process the request without needing to know which object will ultimately handle it, enabling greater flexibility and scalability in system design.
Command: In design patterns, a command is a behavioral pattern that encapsulates a request as an object, allowing for parameterization of clients with different requests, queuing of requests, and logging of the operations. This pattern is particularly useful for implementing undoable operations and decoupling the sender of a request from its receiver, which promotes more flexible and maintainable code.
Component-based architecture: Component-based architecture is a design approach that focuses on creating software applications by assembling reusable, independent components that encapsulate specific functionality. This method promotes modularity, making it easier to manage, update, and maintain complex systems by allowing developers to work on individual components without impacting the entire application.
Composite: In design patterns, a composite is a structural pattern that allows you to compose objects into tree structures to represent part-whole hierarchies. This design pattern enables clients to treat individual objects and compositions of objects uniformly, making it easier to manage complex structures without worrying about the specific types of objects involved.
Creational Patterns: Creational patterns are design patterns that deal with object creation mechanisms, aiming to create objects in a manner suitable to the situation. These patterns abstract the instantiation process, making it more flexible and efficient by separating the specifics of object creation from the system's overall design. They help manage the complexities involved in creating and managing objects, especially when dealing with various types of objects and their relationships.
Decorator: A decorator is a design pattern that allows behavior to be added to individual objects, either statically or dynamically, without affecting the behavior of other objects from the same class. This pattern is useful for enhancing functionality in a flexible and reusable way, making it easier to modify or extend behavior by wrapping an object with additional responsibilities. It promotes adherence to the Single Responsibility Principle by allowing each class to focus on a specific task while allowing combinations of behavior through decorators.
Design Pattern Language: A design pattern language is a structured method of describing and organizing design patterns, which are reusable solutions to common design problems. It connects various patterns through a cohesive framework, enabling designers and developers to effectively communicate their ideas and practices. By utilizing a design pattern language, teams can streamline their processes, foster collaboration, and ensure consistency across different projects.
Encapsulation: Encapsulation is a fundamental concept in object-oriented programming that restricts direct access to an object's internal state and behavior. This principle allows objects to maintain their integrity by hiding their internal workings and exposing only what is necessary through well-defined interfaces. It also supports modularity, as changes made to an object's implementation do not affect other parts of a system that interact with it.
Facade: In design, a facade refers to the exterior front of a building or structure, often emphasizing aesthetic appeal and functionality. Facades are critical in shaping first impressions and are designed to balance both visual elements and structural requirements, playing a significant role in how users interact with the environment.
Factory method: The factory method is a design pattern that provides an interface for creating objects in a superclass, but allows subclasses to alter the type of objects that will be created. This pattern promotes loose coupling in software design by allowing a class to delegate the responsibility of instantiation to subclasses. It helps in managing and scaling complex systems by enabling different implementations to be produced from a common interface.
Flyweight: The Flyweight is a structural design pattern that aims to minimize memory usage by sharing common parts of objects instead of creating separate instances for each. This pattern is especially useful when dealing with a large number of objects that share similar states, allowing for efficient memory management and improved performance. By separating the intrinsic state (shared) from the extrinsic state (unique), the Flyweight pattern helps optimize resource utilization in applications.
Gamma et al.: Gamma et al. refers to a specific method or model in design patterns that emphasizes the importance of flexibility and extensibility in software design. This concept highlights how different components of a system can interact and be reused effectively, allowing designers to create solutions that can adapt to changing requirements or environments. Understanding gamma et al. is crucial for implementing best practices in object-oriented design, as it encourages developers to think about the overall architecture and relationships between various classes and objects.
Interface design patterns: Interface design patterns are standardized solutions to common user interface problems that help improve usability and enhance user experience. These patterns provide a blueprint for creating interfaces that are intuitive, consistent, and aesthetically pleasing, allowing designers to effectively communicate functionality and guide users through their tasks. By using these established patterns, designers can reduce cognitive load and increase efficiency in navigation and interaction.
Interpreter: An interpreter is a type of software that executes instructions written in a programming language, translating code into machine language line by line during runtime. This allows for immediate execution and debugging, making it easier for developers to test their code without the need for a separate compilation step. Unlike compilers, interpreters provide flexibility in development and can enhance productivity through quick iterations.
Iterator: An iterator is an object that enables sequential access to elements in a collection without exposing the underlying structure of the collection. It provides a way to traverse through the elements one at a time, simplifying tasks like iteration over arrays or lists. This concept is essential for implementing various design patterns, as it promotes flexibility and decouples the iteration logic from the data structure being accessed.
Maintainability: Maintainability refers to the ease with which a system or component can be modified to correct faults, improve performance, or adapt to a changed environment. This concept is crucial for ensuring that design patterns and design tokens can be easily updated or enhanced without extensive rework. High maintainability leads to reduced costs and time when implementing changes, making it an essential aspect of efficient design practices.
Martin Fowler: Martin Fowler is a renowned author, speaker, and thought leader in software development, particularly known for his work on software design patterns and agile methodologies. He has contributed significantly to the understanding of design patterns, which are standard solutions to common problems in software design, enhancing developers' ability to create flexible and reusable code. His insights help bridge the gap between theoretical concepts and practical applications, making complex ideas accessible to developers at all levels.
Mediator: A mediator is a design pattern that acts as an intermediary between different components in a system, facilitating communication and reducing direct dependencies. This pattern helps to simplify the interactions among components, promoting loose coupling and enhancing maintainability. By centralizing the communication, a mediator can help manage complex relationships and make changes easier to implement without affecting all components involved.
Memento: Memento is a design pattern used in software development that allows for the capture and external storage of an object's state so that it can be restored later without violating encapsulation. This pattern is particularly useful in scenarios where objects undergo complex changes and a mechanism is needed to revert to a previous state. It promotes the idea of separating the object’s state management from the object itself, enhancing maintainability and flexibility in code design.
Observer: In software design, an observer is a behavioral design pattern that defines a one-to-many dependency between objects, so that when one object changes state, all its dependents are notified and updated automatically. This pattern is especially useful in applications where multiple components need to be informed about changes in the state of another object without tightly coupling those components.
Pattern Catalog: A pattern catalog is a systematic collection of design patterns that provide reusable solutions to common design problems across various contexts. It serves as a reference guide for designers and developers, helping them identify and implement proven strategies that enhance usability, functionality, and user experience. A well-organized pattern catalog simplifies the design process by offering a visual and textual representation of these patterns, making it easier to apply them in projects.
Polymorphism: Polymorphism is a core concept in programming that allows objects of different classes to be treated as objects of a common super class. It enables a single interface to control access to a general class of actions, making code more flexible and reusable by allowing methods to operate on different types without knowing their specific details beforehand.
Prototype: A prototype is an early sample or model of a product that is used to test concepts, design features, and usability before full-scale production. Prototyping helps designers and teams visualize and refine their ideas, allowing for iterative improvements and better alignment with user needs. It serves as a bridge between initial concepts and final products, facilitating feedback and experimentation throughout the design process.
Proxy: A proxy is an intermediary or substitute that acts on behalf of another entity to facilitate communication or decision-making processes. In design patterns, the proxy pattern allows an object to represent another object, providing a surrogate or placeholder to control access to it. This is useful for implementing lazy loading, access control, logging, and other functionalities without changing the original object's interface.
Refactoring: Refactoring is the process of restructuring existing computer code without changing its external behavior. This practice is crucial in software development as it improves code readability and reduces complexity, making future modifications easier and safer. By applying refactoring techniques, developers can enhance design patterns, promote code reuse, and facilitate better collaboration among team members.
Reusability: Reusability refers to the practice of using existing components or patterns in new applications or designs to save time, reduce costs, and maintain consistency. This concept is essential in design and software development as it promotes efficiency and minimizes redundancy, allowing designers and developers to focus on creating unique features rather than starting from scratch.
Scalability: Scalability refers to the capacity of a system, product, or process to handle a growing amount of work or its potential to be enlarged to accommodate that growth. In design and software development, scalability emphasizes the importance of creating solutions that remain effective as demands increase, whether through additional features or increased user loads. It impacts how designs adapt over time, ensuring consistency and efficiency even as complexity grows.
Scrum: Scrum is an agile framework for managing and completing complex projects, emphasizing teamwork, accountability, and iterative progress. It allows teams to deliver small, functional pieces of a product in short cycles called sprints, enabling frequent reassessment and adaptation of plans. Key components include defined roles, ceremonies, and artifacts that help streamline the workflow and enhance collaboration among team members.
Singleton: A singleton is a design pattern that restricts the instantiation of a class to one single instance. This pattern is particularly useful when exactly one object is needed to coordinate actions across the system, ensuring that there is a single point of control. By managing access to this instance, the singleton pattern helps prevent issues related to multiple instances that could lead to inconsistency and unexpected behavior.
State: In design and software contexts, a state refers to a specific condition or situation of an object or system at a given moment. This concept is crucial because it helps define how an object behaves and interacts with other objects or users based on its current attributes and values. Understanding the state allows designers and developers to create more dynamic and responsive systems that can change behavior depending on user input or internal conditions.
Strategy: Strategy refers to a plan of action designed to achieve a specific goal or set of objectives. In the context of design patterns, strategy involves selecting and implementing the best approach to solve a particular design problem, ensuring that the resulting patterns are effective and efficient in meeting user needs and enhancing overall system functionality.
Structural Patterns: Structural patterns are design solutions that provide a way to organize and structure code in software development, facilitating the interaction between different components. These patterns help improve code reusability, readability, and maintainability by establishing clear relationships between classes and objects. They enable developers to create flexible and efficient systems by promoting best practices in design.
Template Method: The Template Method is a design pattern that defines the skeleton of an algorithm in a base class, allowing subclasses to override specific steps without changing the overall structure. This pattern promotes code reusability and makes it easier to manage common behavior among related classes while enabling customization through subclassing.
User-Centered Design: User-centered design is an approach that prioritizes the needs, preferences, and limitations of end-users at every stage of the design process. This methodology emphasizes understanding user behaviors and experiences to create products that are both effective and enjoyable to use.
Visitor: In software design, a Visitor is a design pattern that allows you to separate an algorithm from the objects on which it operates. This pattern enables you to define new operations without changing the classes of the elements on which it operates, making it easier to add functionality to existing systems. The Visitor pattern promotes flexibility and extensibility in systems, allowing for new operations to be added as new visitor classes without modifying the existing object structure.