语法糖
定义 getter setter，在类方法前使用关键字 get/set；
使用 @ 符号，引用 Decorator：
使用模版字符串：
StackOverflow
来自 StackOverflow 上的大神教程。
如何得到一个类派生出的所有子类型：https://stackoverflow.com/questions/42414045/how-to-get-child-classes-which-implement-a-certain-base-class-using-reflection-i
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| export default function hierarchyTracked(target: new (...args: any[]) => object) {
for (const proto of walkPrototypeChain(target)) {
if (!Object.hasOwnProperty.call(proto, 'extendedBy')) {
const extendedBy: typeof Function.extendedBy = [];
Object.defineProperty(proto, 'extendedBy', {
get: () => extendedBy
});
}
// ! is used to suppress a strictNullChecks error on optional.
// This is OK since we know it is now defined.
proto.extendedBy!.push(target);
}
}
declare global {
interface Function {
// Declared as optional because not all classes are extended.
extendedBy?: Array<new (...args: any[]) => object>;
}
}
function* walkPrototypeChain(target: new (...args: any[]) => object) {
let proto = Reflect.getPrototypeOf(target);
while (proto && proto !== Object) {
yield proto;
proto = Reflect.getPrototypeOf(proto);
}
}
|
Mixin
Mixin 本身是一种设计模式，它指不通过继承而是通过混入，将一个类的方法添加到另一个类中。这通常用于解决多继承的问题（一个子类不能同时继承两个基类）。
TypeScript 官方文档给出了一个 mixin 的方法：https://www.typescriptlang.org/docs/handbook/mixins.html：
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| // Each mixin is a traditional ES class
class Jumpable {
jump() {}
}
class Duckable {
duck() {}
}
// Including the base
class Sprite {
x = 0;
y = 0;
}
// Then you create an interface which merges
// the expected mixins with the same name as your base
interface Sprite extends Jumpable, Duckable {}
// Apply the mixins into the base class via
// the JS at runtime
applyMixins(Sprite, [Jumpable, Duckable]);
let player = new Sprite();
player.jump();
console.log(player.x, player.y);
// This can live anywhere in your codebase:
function applyMixins(derivedCtor: any, constructors: any[]) {
constructors.forEach((baseCtor) => {
Object.getOwnPropertyNames(baseCtor.prototype).forEach((name) => {
Object.defineProperty(
derivedCtor.prototype, name,
Object.getOwnPropertyDescriptor(baseCtor.prototype, name) ||
Object.create(null)
);
});
});
}
|