1. DRY (Don’t Repeat Yourself)

Inheritance:

• BaseMoney contains common logic for currencies (EuroMoney, UAHMoney), preventing code duplication when working with money.

Interfaces:

• Using IProduct, IWarehouse, IMoney, IReporting allows splitting responsibilities between classes and avoids method duplication.

Methods:

• The method GenerateInventoryReport() in Reporting centralizes report generation, instead of having each class implement this logic individually.

2. KISS (Keep It Simple, Stupid)

Clarity:

• Classes have clear responsibilities (Product for products, Warehouse for inventory, DeliveryLogger for logging deliveries, etc.).

Minimal Complexity:

• Logging (DeliveryLogger, ShipmentLogger) is separated from Warehouse, making the code simpler.

Additional Simplifications:

• Instead of creating a separate method for printing object fields, the ToString() method is overridden in BaseMoney and Product classes.

3. S - Single Responsibility Principle (SOLID)

Each class has one responsibility:

• Product — product description.
• Warehouse — warehouse management.
• BaseMoney and its descendants — representing monetary units.
• DeliveryLogger and ShipmentLogger — event logging.
• Reporting — report generation.

4. O - Open/Closed Principle (SOLID)

Extensibility without modifying existing code:

• Currency handling logic can be extended by adding new classes (USDMoney, CryptoMoney) without changing BaseMoney.
• New logging types can be added by implementing IWarehouseOperationLogger without modifying Warehouse.

5. L - Liskov Substitution Principle (SOLID)

The base class can be replaced by its subclass without changing behavior:

• EuroMoney and UAHMoney are subclasses of BaseMoney, and any IMoney object can be used without changing the logic. If BaseMoney is removed, the code will still work, but common methods (SetParts(), ToString()) would need to be duplicated in each class.

6. I - Interface Segregation Principle (SOLID)

Interfaces are clearly divided and do not contain unnecessary methods:

• IMoney, IProduct, IWarehouse, IReporting, IWarehouseOperationLogger define only the methods they actually need.
• IProduct does not have methods related to the warehouse, and IWarehouse does not deal with product prices.

7. D - Dependency Inversion Principle (SOLID)

Dependencies are used through interfaces:

• IMoney, IProduct, IWarehouse, IReporting, IWarehouseOperationLogger are used as dependencies, allowing easy replacement of implementations without changing the core code (Warehouse, Product, etc.).
• In Program, the objects DeliveryLogger, ShipmentLogger, and Reporting work through interfaces.