homework: 单例模式

  1. class Demo {
  2.     private static instance: Demo;
  3.     private constructor(public name: string) {};
  5.     static getInstance(name: string): Demo {
  6.         if (!this.instance) {
  7.             this.instance = new Demo(name);
  8.         }
  9.         return this.instance;
  10.     }
  11. }
  13. const d1 = Demo.getInstance('Jack');
  14. const d2 = Demo.getInstance('Lily');
  15. console.log(d1.name);
  16. console.log(d2.name);
  18. // Jack
  19. // Jack

homework: 接口重载

Flyweight Pattern（享元模式）：主要用于减少创建对象的数量，以减少内存占用和提高性能。

  1. type OrderID = string & { readonly brand: unique symbol };
  2. type UserID = string & { readonly brand: unique symbol };
  3. type ID = OrderID | UserID;
  5. // (伴侣模式): 一种非正式编程约束
  6. function OrderID (id: string) {
  7.     return id as OrderID;
  8. }
  10. function UserID (id: string) {
  11.     return id as UserID;
  12. }
  14. function queryForUser(id: ID) {}
  16. queryForUser('ll');
  17. // Argument of type 'string' is not assignable to parameter of type 'ID'.ts(2345)
  19. queryForUser(UserID('ll'));