我正在尝试为通用方法的参数添加一些自动完成支持
subscribeToTelemetry<T extends keyof TypeMap>(name: T): Stream<TypeMap[T]>;
subscribeToTelemetry<T extends NonNullable<{}>>(name: EntityName<T>): Stream<T>;
简而言之,如果没有提供类型,subscribeToTelemetry
则应根据名称和一些可用的注入/自动生成类型推断返回类型。此外,应使用可用的注入/自动生成类型提出可能的名称建议。例如,使用以下类型:
type TypeMap = {
ranger1: RangerTelemetry,
ranger2: RangerTelemetry,
mavic2: DroneTelemetry
};
以及以下代码
// should suggest: ['mavic2' | 'ranger2' | 'ranger1'] since no type T is provided
const myStream1 = r.subscribeToTelemetry('ranger1'); // myStream1: Stream<RangerTelemetry
建议值应为 ['mavic2' | 'ranger2' | 'ranger1'],因为未提供类型 T,并且 myStream1 类型将是Stream<RangerTelemetry>
相反,如果我们提供一个类型subscribeToTelemetry
,并考虑可用的注入/自动生成类型
const entityNames = {
RangerTelemetry: ['ranger1', 'ranger2', 'ranger3'],
DroneTelemetry: ['mavic1', 'mavic2', 'mavic3'],
} as const;
和其他一些类型的技巧(参见操场链接),使用以下代码
// should suggest only: ['mavic1' | 'mavic2' | 'mavic3'] since type T is provided as DroneTelemetry,
const myStream3 = r.subscribeToTelemetry<DroneTelemetry>('mavic1');
我们应该建议:['mavic1' | 'mavic2' | 'mavic3'],因为提供了类型DroneTelemetry
,但显示的却是 ['mavic1' | 'mavic2' | 'mavic3', 'ranger1', 'ranger2', 'ranger3']。的类型myStream3
将是Stream<DroneTelemetry>
我有多个重载方法的签名实现变体,但 subscribeToTelemetry
在提供类型时无法提供正确的建议,即使我指定 DroneTelemetry
为类型,我总是会得到游骑兵的建议。
class Registry {
subscribeToTelemetry<T extends keyof TypeMap>(name: T): Stream<TypeMap[T]>;
subscribeToTelemetry<T extends NonNullable<{}>>(name: EntityName<T>): Stream<T>;
subscribeToTelemetry<T extends NonNullable<{}>>(name: EntityName<T>): Stream<T> {
return new Stream<T>(name);
}
}
如果有人有任何建议,我将不胜感激
温贝托
完整代码如下:
type DroneTelemetry = { kind: 'DroneTelemetry', batteryLevel: number, velocity: number, location: {latitude: number, longitude: number}}
type RangerTelemetry = { kind: 'RangerTelemetry', velocity: number, location: {latitude: number, longitude: number}}
////// the entity names and type mapping will be autogenerated
const entityNames = {
RangerTelemetry: ['ranger1', 'ranger2', 'ranger3'],
DroneTelemetry: ['mavic1', 'mavic2', 'mavic3'],
} as const;
type TypeMap = {
ranger1: RangerTelemetry,
ranger2: RangerTelemetry,
mavic2: DroneTelemetry
};
////////
// Define the types for the keys and values of the mapping
type EntityNames = typeof entityNames;
type EntityKeys = keyof EntityNames;
type EntityValues<T extends EntityKeys> = EntityNames[T][number];
// Define a mapping from type aliases to their corresponding keys
type TypeToKey<T> = T extends { kind: infer K } ? K : never;
type ExtractEntitiesNames<T> = TypeToKey<T> extends keyof EntityNames ? EntityValues<TypeToKey<T>> : never;
type EntityName<T> = ExtractEntitiesNames<T> | (string & {});
/////////////////////////////////////////////////////////////////////
class Stream<T> {
name: string
constructor(name: string){
this.name = name
}
getLastValue() {
return {} as T // dummy impl
}
}
class Registry {
subscribeToTelemetry<T extends keyof TypeMap>(name: T): Stream<TypeMap[T]>;
subscribeToTelemetry<T extends NonNullable<{}>>(name: EntityName<T>): Stream<T>;
subscribeToTelemetry<T extends NonNullable<{}>>(name: EntityName<T>): Stream<T> {
return new Stream<T>(name);
}
}
const r = new Registry();
// should suggest: ['mavic2' | 'ranger2' | 'ranger1'] since no type T is provided // OK
const myStream1 = r.subscribeToTelemetry('ranger1'); // myStream1 type will be Stream<RangerTelemetry>
// should suggest: ['mavic2' | 'ranger2' | 'ranger1'] since no type T is provided // OK
const myStream2 = r.subscribeToTelemetry('ranger2'); // myStream2 type will be Stream<RangerTelemetry>
// should suggest only: ['mavic1' | 'mavic2' | 'mavic3'] since type T is provided as DroneTelemetry,
// but ['mavic1' | 'mavic2' | 'mavic3', 'ranger1', 'ranger2', 'ranger3'] is shown instead. // WRONG
const myStream3 = r.subscribeToTelemetry<DroneTelemetry>('mavic1'); // myStream3 type will be Stream<RangerTelemetry>
这是一个包含完整代码的ts-playground
我们可以通过改变类型相互映射的方法来解决这个问题。代码中会比解释中更容易看到这一点。使用这种方法,您不需要重载函数。
该方法的摘要:
TypeMap
(Record<> or {[x in key]: value}
其中无人机名称的值为,DroneTelemetry
护林员名称的值为subscribeToTelemetry
T
是实体类型DroneTelemetry|RangerTelemetry
F
是基于 的实体名称T
,当不通过定义或推断缩小范围时,它将是所有实体名称。当通过传递的 缩小范围时T
,由于 ,它只是与实体类型相关的键EntityName
。这不仅对参数自动完成有用,而且对返回类型也很有用,如下一点所述。F
给TypeMap
获取返回的EntityType
T
没有传递,F
则将推断出匹配的类型T
,我们不想传递F
(太忙乱),所以我们有一个默认类型,它缩小到仅属于该实体类型的名称,这意味着我们已经缩小了传递给的键TypeMap
,返回相关的EntityType
需要注意的是,第二个泛型类型 F 是在不传递 T 时推断出来的,但是传递 T 时必须传递F,因为你不能传递一些泛型类型然后推断出其余的,要么全部,要么全部都没有。这就是为什么我们需要给出
F
一个默认类型。操场