获得徽章 17
- 评论点赞
- #每天一个知识点#
export declare class TagProtector<T extends string> {
protected __tag__: T;
}
export type Nominal<T, U extends string> = T & TagProtector<U>;
export type USD = Nominal<number, 'USD'>;
export type CNY = Nominal<number, 'CNY'>;
const CNYCount = 100 as CNY;
const USDCount = 100 as USD;
function addCNY(source: CNY, input: CNY) {
return (source + input) as CNY;
}
addCNY(CNYCount, CNYCount);
// 报错了！
addCNY(CNYCount, USDCount);
没太懂怎么实现标准化类型系统，使用联合类型为啥展开评论点赞
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