简体   繁体   English

泛型的返回类型 function

[英]Return type of generic function

I'm trying to make getResults function return the proper type, but currently stuck with this:我试图让getResults function 返回正确的类型,但目前坚持这样做:

interface IResponse<T> {
    result: T;
}

type FnType<P, R> = (params: P) => R;

const r1: IResponse<string[]> = { result: ['123'] };
const r2: IResponse<number[]> = { result: [456] };

const getResults = <T, R extends IResponse<T[]>, P>(fn: FnType<P, R>, params: P): T[] => {
    return [
        ...fn(params).result,
        ...fn(params).result
    ];
};

const getValue = <T>(r: IResponse<T>) => r;

// returned type is unknown[]
// how can we make it return string[]?
getResults(getValue, r1);

// returned type is unknown[]
// how can we make it return number[]?
getResults(getValue, r2);

Playground 操场

The code is just an example, in the production getResults function is used to merge results from a paginated request ( fn in this case is a request function)该代码只是一个示例,在生产中getResults function 用于合并分页请求的结果( fn在这种情况下是请求函数)

So, I'm not sure this will also cover the things you need for production.所以,我不确定这是否也涵盖了您生产所需的东西。 But the return type looks alright like this:但是返回类型看起来像这样:

interface IResponse<T> {
    result: T;
}

type FnType<P, R> = (params: P) => R;

const r1: IResponse<string[]> = { result: ['123'] };
const r2: IResponse<number[]> = { result: [456] };

const myResults = <P,R>(fn: FnType<P,IResponse<R[]>>, params: P): R[] => {
     return [
        ...fn(params).result,
        ...fn(params).result
    ];
}

const getValue = <T>(r: IResponse<T>) => r;

myResults(getValue, r1);

myResults(getValue, r2);

Playground link 游乐场链接

Edit: I'm actually not exactly sure why the code in question does not give correct IntelliSense, it makes sense to me.编辑:我实际上不确定为什么有问题的代码没有提供正确的 IntelliSense,这对我来说很有意义。

But what I can see is that you used three generic types T , R and P .但我可以看到,您使用了三种泛型类型TRP My Idea is that basically you only have 2 types to worry about which are params and the Result of the method.我的想法是,基本上你只有 2 种类型需要担心,它们是参数和方法的结果。

I basically say, whatever type is inside the getValue 's IResponse will be the final output of the myResults function.我基本上是说, getValueIResponse中的任何类型都将是 myResults function 的最终myResults

声明:本站的技术帖子网页,遵循CC BY-SA 4.0协议,如果您需要转载,请注明本站网址或者原文地址。任何问题请咨询:yoyou2525@163.com.

 
粤ICP备18138465号  © 2020-2024 STACKOOM.COM