The Five principles of OO

1. Single Duty principle

There should be and only one cause for class change

2, the Richter replacement principle

All references to base classes must be able to transparently use objects of their subclasses

3. Dependency Inversion principle

High-level modules should not rely on the underlying modules, both should rely on abstraction; abstractions should not depend on detail; detail should be dependent on abstraction

4. Interface Isolation principle

Inter-class dependencies should be built on the interface, a single interface should not be built, and the interface should be as thin as possible.

5. Opening and closing principle

The software should be open to extensions, closed for modification, and should be extended to make changes, and should not be changed by modifying existing code