solid

Five principles for building software that is easy to understand, extend, and maintain. They reduce coupling, increase cohesion, and make code testable.

| SRP | One reason to change | "This class handles X and Y and Z" | | OCP | Add, don't modify | Growing if/else or switch chains for types | | LSP | Subtypes are substitutable | Type-checking or special-casing in calling code | | ISP | Small, focused interfaces | Empty method implementations or throw new Error("Not implemented") |

| DIP | Depend on abstractions | new ConcreteClass() inside business logic |

应用 SOLID 原则编写灵活、可维护和可测试的代码。 在设计类、接口和模块边界时使用。封面单曲 责任、开放/封闭、里氏替换、接口隔离和 依赖倒置与实用的 TypeScript 示例和检测启发式。 来源：fellipeutaka/leon。