Project Introduction: DesignPatterns
The "DesignPatterns" project is an exploration of the 23 design patterns popularized by the "Gang of Four" in their seminal book, "Design Patterns: Elements of Reusable Object-Oriented Software." These patterns are widely recognized as powerful solutions to common software design problems. The project categorizes these design patterns into three broad groups: Behavioral, Creational, and Structural. Below is an in-depth look at each group and its respective patterns.
Behavioral Patterns
Behavioral patterns focus on ways objects interact and communicate with each other. They help make complex object interactions manageable and increase flexibility in carrying out communication.
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Chain of Responsibility: This pattern allows multiple objects a chance to handle a request, preventing tight coupling between the sender and receiver.
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Command: By encapsulating a request as an object, this pattern provides the flexibility to parameterize, queue, or log requests and supports operations that can be undone.
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Interpreter: It defines a representation for the grammar of a language and uses an interpreter to process sentences in that language.
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Iterator: It offers a way to traverse through elements of a collection without revealing the underlying structure of the collection.
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Mediator: This pattern introduces a mediator object to control interaction and communication between a collection of objects, limiting direct references and dependencies.
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Memento: It allows capturing an object's internal state without breaking encapsulation so the object can be restored later.
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Observer: Establishing a one-to-many relationship, this pattern updates all dependent objects automatically when the state of one object changes.
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State: This pattern lets an object alter its behavior as its state changes, letting it appear as if it changes its class.
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Strategy: It defines a family of interchangeable algorithms, promoting easy switchability and independence from the client.
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Template Method: It lets subclasses redefine specific steps of an algorithm, allowing for some customization without altering the algorithm’s structure.
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Visitor: It allows defining a new operation on elements of an object structure without changing the objects themselves.
Creational Patterns
Creational patterns deal with the process of object creation, aiming to make systems more independent of how their objects are composed and represented.
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Abstract Factory: This provides an interface for creating families of related objects without specifying their concrete classes.
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Builder: This pattern separates the construction of a complex object from its representation, facilitating creation with different representations.
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Factory Method: By defining an interface, it allows subclasses to specify which concrete class to instantiate, deferring creation.
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Prototype: It allows new objects to be created by copying a prototypical instance, reducing the overhead of creating objects from scratch.
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Singleton: This pattern ensures a class has only one instance and provides a global point of access to it.
Structural Patterns
Structural patterns are about organizing objects and classes to form larger structures, ensuring flexibility and efficiency.
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Adapter: It enables classes with incompatible interfaces to work together by translating one interface to another.
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Bridge: This pattern decouples an abstraction from its implementation, allowing them to evolve independently.
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Composite: By organizing objects into tree structures, it treats individual objects and compositions uniformly, simplifying part-whole hierarchies.
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Decorator: It dynamically adds responsibilities to an object, offering a flexible alternative to subclassing for extending functionality.
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Facade: It provides a unified and simplified interface to a set of interfaces within a system, easing its use.
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Flyweight: This pattern makes efficient use of memory by sharing objects among multiple contexts where appropriate.
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Proxy: It offers a surrogate or placeholder to control access to another object, adding an additional layer of control.
Each of these design patterns provides a specific solution to a specific design problem or requirement, reducing software complexities and enhancing its extendibility and maintainability. The "DesignPatterns" project serves as a comprehensive resource for understanding and implementing these critical solutions in software design.