Design patterns are reusable solutions to commonly occurring software design problems. They provide a way to create robust, flexible, and reusable software architectures. In this repository, we have examples of design patterns that fall into one of the three main categories: creational, structural, and behavioral patterns.
Creational patterns deal with the process of object creation. These patterns provide ways to create objects while hiding the creation logic, abstracting the creation process, or even deferring object creation to another object.
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Singleton Pattern: This pattern ensures that only one instance of a class exists in the system and provides a global point of access to that instance. For example, a database connection or a logging mechanism can be implemented using the Singleton pattern.
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Factory Method Pattern: This pattern provides an interface for creating objects, but allows subclasses to alter the type of objects that will be created. For example, a web application might use a factory method to create different types of database connections, depending on the type of database being used.
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Abstract Factory Pattern: This pattern provides an interface for creating families of related or dependent objects without specifying their concrete classes. For example, a GUI toolkit might use an abstract factory to create different types of buttons, text boxes, and other graphical elements for different operating systems.
Structural patterns deal with the composition of classes and objects to form larger structures. They describe how objects and classes can be combined to form new structures and provide mechanisms to manage the relationships between them.
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Adapter Pattern: This pattern allows incompatible interfaces to work together by creating an adapter object that acts as a bridge between them. For example, an adapter can be used to connect a new version of a software component to an older version that has a different interface.
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Composite Pattern: This pattern allows you to treat a group of objects as a single object. The composite pattern creates a tree structure of objects where each node in the tree can be either a composite object or a leaf object. For example, a file system can be represented as a composite object, where a folder can contain both files and other folders.
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Decorator Pattern: This pattern allows you to add behavior to an object dynamically without changing its class. The decorator pattern involves creating a wrapper class around an object, which allows you to add new functionality at runtime. For example, a GUI toolkit might use a decorator to add a border or a shadow effect to a graphical element.
Behavioral patterns deal with the communication between objects and classes. They describe how objects interact with one another and provide mechanisms for controlling that interaction.
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Observer Pattern: This pattern defines a one-to-many dependency between objects, so that when one object changes state, all its dependents are notified and updated automatically. For example, a stock market application might use the observer pattern to notify users when a particular stock's value changes.
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Command Pattern: This pattern encapsulates a request as an object, thereby allowing you to parameterize clients with different requests, queue or log requests, and support undoable operations. For example, a text editor might use the command pattern to allow users to undo or redo actions.
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Strategy Pattern: This pattern defines a family of algorithms, encapsulates each one, and makes them interchangeable. Strategy lets the algorithm vary independently from clients that use it. For example, a payment processing system might use different strategies for processing credit card payments and PayPal payments.
While there may be some overlap in what structural and behavioral patterns can accomplish, they serve different purposes and solve different types of problems. Here are some real-life examples to help illustrate the differences between structural and behavioral patterns:
Structural patterns deal with the composition of classes and objects to form larger structures. They describe how objects and classes can be combined to form new structures and provide mechanisms to manage the relationships between them.
Behavioral patterns deal with the communication between objects and classes. They describe how objects interact with one another and provide mechanisms for controlling that interaction.
While in some cases, the patterns may overlap in terms of the problems they solve, they each represent different types of problems and require different solutions. Structural patterns deal with the composition of classes and objects, while behavioral patterns deal with the interaction between them.
In summary, design patterns provide proven solutions to common software design problems. The creational, structural, and behavioral patterns are the three main categories of design patterns, each with its own