基于另一个通用参数的类型对象参数

Question

我正在尝试根据打字稿中的另一个通用参数动态键入一个参数。

这是为了构建一个自定义测试框架，它将要测试的方法、它的参数和预期结果作为参数。

// function that tests if the method return an expected result 
const myCustomTest = (arg: { method: (...arg: any[]) => any, arguments: any, response: any }) => {
    const { method, arguments, response } = arg;
    return method.apply(null, arguments) === response; // suppose this is a sync function
};

// given a function test1
const test1 = (arg: number, arg2: boolean): boolean => {
    return true;
};

// then the linter should raise
myCustomTest({ method: test1, arg: [12, 12], response: true }); // wrong, second parameter is a number and not a boolean
myCustomTest({ method: test1, arg: [12, false], response: true }); // OK

// It could work with
type Arguments<T> = T extends (...args: infer U) => any ? U : any;

const myCustomTest = (arg: { method: (...arg: any[]) => any, arguments: Arguments<typeof test1>, response: ReturnType<typeof test1> }) => {
    const { method, arguments, response } = arg;
    return method.apply(null, arguments) === response; // suppose this is a sync function
};

但是我想找到一种方法来根据传入参数的方法的参数来键入参数和响应。

提前致谢！

Answer 1

您真的很接近解决方案了！通过一些小的调整，编译和类型检查。您必须确保将通用类型参数添加到 myCustomTest 函数：

type Arguments<T> = T extends (...args: infer U) => any ? U : never;

const myCustomTest = <T extends (...args: any) => any>(arg: { method: T, parameters: Arguments<T>, response: ReturnType<T>}) => {
    const { method, parameters, response } = arg;
    return method.apply(null, parameters) === response; // suppose this is a sync function
};

请参阅 this Typescript Playground 中的完整示例！

基于另一个通用参数的类型对象参数

Type object parameter based on another generic parameter

typescript

typescript-generics

typescript-typings