📚 Design Patterns Showcase – Library Management System

This is a student project that explores core object-oriented design patterns through the context of a simple library management system. The goal was not to create a polished application, but to demonstrate the application of patterns like Decorator, Factory, Strategy, and Observer in a realistic but minimal use case.

Originally implemented as a Windows Forms app, it has been refactored to a console application to better focus on showcasing the design logic.

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🧠 Patterns Demonstrated

• Factory Pattern: Used to instantiate different types of books (NovelFactory, MagazineFactory) based on context.
• Decorator Pattern: Adds dynamic functionality to books, such as:
  • LateFeeDecorator: Applies a late fee when a book is returned.
  • BorrowingPeriodExtensionDecorator: Extends the loan period.
• Strategy Pattern: Controls the loan duration depending on the borrower:
  • StudentLoanStrategy
  • LibraryStaffLoanStrategy
• Observer Pattern: Notifies library users when books become available.

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🧪 Example Features

• Register students and library staff as observers.
• Create books and add them to inventory.
• Borrow and return books with different loan strategies.
• Apply decorators to alter book behavior at runtime.
• Get notified when a borrowed book is returned.

🚀 How to Run

Clone the repository:

git clone https://github.com/yourusername/DesignPatterns.git

• Open the DesignPatterns.sln file in Visual Studio 2022 or later.
• Ensure the project targets .NET 6.