| Principle | Description | Details |
|---|---|---|
| Single Responsibility Principle (SRP) | A module/class/function should have one and only one reason to change. | - |
| Open/Closed Principle (OCP) | Classes, modules, functions, should be open for extension, but closed for modification. | Open: - We can add new features to our classes. - When new requirements come, we should be able to add new features to our class easily. Closed: - The base features of the class should not be changed. |
| Liskov Substitution Principle (LSP) | If S is a subtype of T, then objects of type T in a program may be replaced with objects of type S without altering any of the desirable properties of that program. | Objects in a program should be replaceable with instances of their subtypes without altering the correctness of that program. |
| Interface Segregation Principle (ISP) | Clients should not be forced to depend on methods that they do not use. | - A class should perform only actions that are needed to fulfill its role. - Any other action should be removed completely or moved somewhere else if it might be used by another class in the future. - This principle advocates for splitting a set of actions into smaller sets so that a class executes only the set of actions it requires. |
| Dependency Inversion Principle (DIP) | - High-level modules should not depend on low-level modules. Both should depend on the abstraction. - Abstractions should not depend on details. Details should depend on abstractions. |
Summary: - High-level modules: Depend on abstractions. - Low-level modules: Depend on abstractions, not details. |