Self-study C#04 from scratch--Features and design principles

1. Three major features

Encapsulation: Hide internal implementation.
Inheritance: Reuse existing code.
Polymorphism: rewrite object behavior.

2. Design principles

• ##Single Responsibility Principle(SRP)

A class has only one cause of it Reason for change.

• Open-Close Principle (OCP):

Class modules should be extensible, but cannot be modified. (Open to extension development, closed to modifications)

• Liskov Substitution Principle(LSP):

Subclasses can be anywhere Replace its base class.

• Interface Segregation Principle (ISP):

Try to use interfaces with single functions instead of interfaces with complex and comprehensive functions .

• Dependence Inversion Principle (DIP):

High-level modules should not depend on low-level modules, both should depend on abstraction . Abstractions should not depend on implementation details; implementation details should depend on abstractions.

• Law of Demeter or Least Knowledge Principle(LOD orLKP):

Requires as much encapsulation as possible, as much as possible Independent, try to use low-level access modifiers.

• Composition/Aggregation Reuse Principle (CARP):

If you only achieve the purpose of code reuse, try to use it Composition and aggregation, not inheritance.

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