前端 - TypeScript创造的联合类型(Mixin)中，如何支持 prototype链判断？如何让 isInherit(C, A) 和 isInherit(C, B) 判定同时成立？

Question

TypeScript Mixin 创造的联合类型中，如何支持 prototype 链支持？

type Constructor<T = Record<string, any>> = new (...args: any[]) => T;type UnionToIntersection<U> = (U extends any ? (k: U) => void : never) extends (k: infer I) => void ? I : never;function Mixin<T extends Constructor[]>(...mixins: T): Constructor<UnionToIntersection<InstanceType<T[number]>>> & UnionToIntersection<T[number]>;function Mixin<T extends Constructor[]>(...mixins: T) {    class Mix { }    const mergeDesc: any = {};    function copyProperties(target: any, source: any) {        for (let key of Reflect.ownKeys(source)) {            if (key !== 'constructor' && key !== 'prototype' && key !== 'name') {                let desc = Object.getOwnPropertyDescriptor(source, key);                if (desc) {                    mergeDesc[key] = mergeDesc[key] || [];                    mergeDesc[key].push(desc.value);                    Object.defineProperty(target, key, desc);                }            }        }    }    for (let mixin of mixins) {        copyProperties(Mix, mixin); // 拷贝静态属性        copyProperties(Mix.prototype, mixin.prototype); // 拷贝原型属性    }    for (const key in mergeDesc) {        const fns = mergeDesc[key];        Object.defineProperty(Mix.prototype, key, {            configurable: true,            enumerable: true,            writable: true,            value(...args: any[]) {                const context = this;                fns.forEach(function (fn: Function) {                    fn.call(context, ...args);                });            },        });    }    return Mix}class A {    printA() {        console.log("A");    }}class B {    printB(sss: string) {        console.log("B");    }}class C extends Mixin(A, B) {    constructor() {        super();    }    printC() {        this.printA();        this.printB('');    }}function isInherit(childClass: any, parentClass: any): boolean {    let child = childClass;    while (child) {        if (child === parentClass) {            return true;        }        child = child.__proto__;    }    return false;}if (isInherit(C, A)) { // 判定不成立    console.log('C inherit A');} else {    console.log('C not inherit A');}if (isInherit(C, B)) { // 判定不成立    console.log('C inherit B');} else {    console.log('C not inherit B');}

Answer 1

type Constructor<T = Record<string, any>> = new (...args: any[]) => T;type UnionToIntersection<U> = (U extends any ? (k: U) => void : never) extends (k: infer I) => void ? I : never;function Mixin<T extends Constructor[]>(...mixins: T): Constructor<UnionToIntersection<InstanceType<T[number]>>> & UnionToIntersection<T[number]> {    class Mix {        static mixinClasses = mixins;    }    const mergeDesc: any = {};    function copyProperties(target: any, source: any) {        for (let key of Reflect.ownKeys(source)) {            if (key !== 'constructor' && key !== 'prototype' && key !== 'name') {                let desc = Object.getOwnPropertyDescriptor(source, key);                if (desc) {                    mergeDesc[key] = mergeDesc[key] || [];                    mergeDesc[key].push(desc.value);                    Object.defineProperty(target, key, desc);                }            }        }    }    for (let mixin of mixins) {        copyProperties(Mix, mixin); // 拷贝静态属性        copyProperties(Mix.prototype, mixin.prototype); // 拷贝原型属性        // 添加标识属性        Mix.prototype[`__is${mixin.name}`] = true;    }    for (const key in mergeDesc) {        const fns = mergeDesc[key];        Object.defineProperty(Mix.prototype, key, {            configurable: true,            enumerable: true,            writable: true,            value(...args: any[]) {                const context = this;                fns.forEach(function (fn: Function) {                    fn.call(context, ...args);                });            },        });    }    return Mix as Constructor<UnionToIntersection<InstanceType<T[number]>>> & UnionToIntersection<T[number]>;}class A {    printA() {        console.log("A");    }}class B {    printB(sss: string) {        console.log("B");    }}class C extends Mixin(A, B) {    constructor() {        super();    }    printC() {        this.printA();        this.printB('');    }}function isInherit(childClass: any, parentClass: any): boolean {    const parentName = parentClass.name;    return childClass.prototype[`__is${parentName}`] === true;}if (isInherit(C, A)) { // 判定成立    console.log('C inherit A');} else {    console.log('C not inherit A');}if (isInherit(C, B)) { // 判定成立    console.log('C inherit B');} else {    console.log('C not inherit B');}