有没有办法在 TypeScript 中创建扩展原始类型的名义类型? [英] Is there a way to create nominal types in TypeScript that extend primitive types?

问题描述

假设我正在跟踪两种类型的数字，例如 latitude 和 longitude.我想用基本的 number 原语表示这些变量，但不允许在打字稿中将 longitude 分配给 latitude 变量.

Say I have two types of numbers that I'm tracking like latitude and longitude. I would like to represent these variables with the basic number primitive, but disallow assignment of a longitude to a latitude variable in typescript.

有没有办法对 number 原语进行子类化，以便打字稿检测到这个分配是非法的?以某种方式强制名义输入以使此代码失败?

Is there a way to sub-class the number primitive so that typescript detects this assignment as illegal? Someway to coerce nominal typing so that this code fails?

var longitude : LongitudeNumber = new LongitudeNumber();
var latitude : LatitudeNumber;
latitude = longitude; // <-- type failure

"如何在打字稿中扩展原始类型的答案?" 似乎它会让我朝着正确的方向发展，但我不确定如何扩展该解决方案来为不同的 种类的数字.

The answer to "How to extend a primitive type in typescript?" seems like it will put me in the right direction, but I am not sure how to extend that solution to create distinct nominal sub-types for different kinds of numbers.

我是否必须包装原语?如果是这样，我可以让它像普通数字一样无缝运行，还是必须引用子成员?我可以以某种方式创建一个打字稿编译时编号子类吗?

Do I have to wrapper the primitive? If so, can I make it behave somewhat seamlessly like a normal number or would I have to reference a sub-member? Can I just somehow create a typescript compile-time number subclass?

推荐答案

没有办法做到这一点.

在 GitHub 网站上跟踪此问题的建议是度量单位.

A suggestion tracking this on the GitHub site is Units of Measure.

在未来的版本中，您将能够使用 type 来定义原语的替代名称，但这些不会有任何与之关联的检查:

In a future release, you'll be able to use type to define alternate names for the primitives, but these will not have any checking associated with them:

type lat = number;
type lon = number;
var x: lat = 43;
var y: lon = 48;
y = 'hello'; // error
x = y; // No error

这篇关于有没有办法在 TypeScript 中创建扩展原始类型的名义类型?的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！