英文:
Typescript, How to constrain types according to function parameters?
问题
如何限制T以符合键的要求。
英文:
What can be done to make the useWatchProps callback function parameters correspond to the first parameter
type KeysToValues<O extends Record<string, any>, K> = K extends [infer G,...infer L]? G extends keyof O? [O[G], ...KeysToValues<O, L>]: []: []function useWatchProps<O extends Record<string, any>,K extends keyof O = keyof O,T extends K | K[] = K | K[]>(keys: T,callback: (values: T extends K ? O[K] : KeysToValues<O, K>) => void) {}useWatchProps<{ a: number; b: string }>('a', (a) => {a // number})useWatchProps<{ a: number; b: string }>(['a', 'b'], ([a, b]) => {a // numberb // string})
How to constrain T by keys
答案1
得分: 0
以下是您要的翻译内容：
"Since you are not passing the T, it gets automatically turned to the default value that you have assigned. Unfortunately, we can't specify only the portion of the required parameters; thus, I can suggest making useWatchProps accept only O and return another function. Usage will look like this:
useWatchProps<{ a: number; b: string }>()('a', (a) => {a; // number});
We will also need to change T to a const type parameter to avoid compiler turning the T to a union. This will cause to turn all checks of the T to readonly some_array/some_tuple.
Modifications:
type KeysToValues<O extends Record<string, any>, K> = K extends readonly [infer G,...infer L,]? G extends keyof O? [O[G], ...KeysToValues<O, L>]: []: K
Implementation:
function useWatchProps<O extends Record<string, any>>() {return <const T extends keyof O | readonly (keyof O)[]>(keys: T,callback: (values: T extends keyof O ? O[T] : KeysToValues<O, T>) => void,) => {};}
Usage:
useWatchProps<{ a: number; b: string }>()('a', (a) => {a; // number});useWatchProps<{ a: number; b: string }>()(['a', 'b'], ([a, b]) => {a; // numberb; // string});
希望这对您有所帮助。
英文:
Since you are not passing the T, it gets automatically turned to the default value that you have assigned. Unfortunately, we can't specify only the portion of the required parameters; thus, I can suggest making useWatchProps accept only O and return another function. Usage will look like this:
useWatchProps<{ a: number; b: string }>()('a', (a) => {a; // number});
We will also need to change T to a const type parameter to avoid compiler turning the T to a union. This will cause to turn all checks of the T to readonly some_array/some_tuple.
Modifications:
type KeysToValues<O extends Record<string, any>, K> = K extends readonly [infer G,...infer L,]? G extends keyof O? [O[G], ...KeysToValues<O, L>]: []: K
Implementation:
function useWatchProps<O extends Record<string, any>>() {return <const T extends keyof O | readonly (keyof O)[]>(keys: T,callback: (values: T extends keyof O ? O[T] : KeysToValues<O, T> ) => void,) => {};}
Usage:
useWatchProps<{ a: number; b: string }>()('a', (a) => {a; // number});useWatchProps<{ a: number; b: string }>()(['a', 'b'] , ([a,b]) => {a; // numberb; // string});
通过集体智慧和协作来改善编程学习和解决问题的方式。致力于成为全球开发者共同参与的知识库，让每个人都能够通过互相帮助和分享经验来进步。
评论