Ecmascript 6 如何组合相交类型和并集类型

需要通过属性

c

来“扩展”基类型

base

。 以下是：

结果由

19: const f = (x: Derived) => {
                  ^ intersection type. This type is incompatible with
17: } & Base;
        ^ union: object type(s)
21:     x.a = 3;
     ^ assignment of property `a`. Property cannot be assigned on any member of intersection type
21:     x.a = 3;
     ^ intersection
24:     x.b = 3;
     ^ assignment of property `b`. Property cannot be assigned on any member of intersection type
24:     x.b = 3;
     ^ intersection

---

除了将同一道具

c

添加到工会的两个成员之外，还有其他解决方案吗？谢谢

您可以将其反转，使

派生的
成为
BaseA
和
BaseB
的并集，并为两个基添加具有交集的公共属性（）：

19: const f = (x: Derived) => {
                  ^ intersection type. This type is incompatible with
17: } & Base;
        ^ union: object type(s)
21:     x.a = 3;
     ^ assignment of property `a`. Property cannot be assigned on any member of intersection type
21:     x.a = 3;
     ^ intersection
24:     x.b = 3;
     ^ assignment of property `b`. Property cannot be assigned on any member of intersection type
24:     x.b = 3;
     ^ intersection

/* @flow */

export type A = 'a1' | 'a2';
export type B = | 'b1' | 'b2' | 'b3' | 'b4';

type Base = {
  c: boolean;
};

type BaseA = Base & {
  a: number,
  type: A,
};

type BaseB = Base & {
  b: number,
  type: B,
};

type Derived = BaseA | BaseB;

const f = (x: Derived) => {
  x.c = true;
  if(x.type === 'a1') {
    x.a = 3;
  }
  if(x.type === 'b1') {
    x.b = 3;
  }
}