在Typescript中强制不变的返回

Question

你好，我想知道是否有可能停止重写类型，使其在编译时保持不可变。

例如，我的意思是让我们创建一个接口

interface freeze{
  frozen: boolean;
}

和深度冻结功能

function deepFreeze<T>(obj: T) {
  var propNames = Object.getOwnPropertyNames(obj);
  for (let name of propNames) {
    let value = (obj as any)[name];
    if (value && typeof value === "object") {
      deepFreeze(value);
    }
  }
  return Object.freeze(obj);
}

如果我现在做这样的东西

function shouldntWork(): freeze  //:freeze is what i want to be blocked as its wrong
{  
 let mutableFreeze: freeze = { frozen:false}
  let immutableFreeze = deepFreeze(mutableFreeze); 
  return immutableFreeze;
}

我知道这不是一个bug，但我想知道是否有某种eslint规则强制不覆盖类型或其他什么，因为我会这样做

function other()  {
  let something = shouldntWork();
  something.frozen = true;
  //will crash at runtime but want it to get blocked at compiletime
    console.log(something);
}

它会崩溃，但如果我没有:freeze，它会推断出正确的只读类型，并在compileTime给出一个错误。

这是Typescript游乐场https://www.typescriptlang.org/play?noImplicitOverride=true#code/JYOwLgpgTgZghgYwgAhlCEBeEDeBYAKGVSgHtsQAuZAI1NIBsI4QBuQgX0MKbGQGdSAWwgAxdFgjU0GbMgC8yHGnIQqqOA34QuBQjACuIBGGCkQAgBakDDACbgA6qSgBrABQBKSjMlLCxAHIvMiQ-JBQCsh2GAAO4rIQ7oIiCZKerMhB6GAGUBZhEewEuvpGJmYWpGCW0F7E+ETBEHwpLZagAOZR-Na2DmDObl7FxG01XQB0KhRRYFAGEKPIAPQrAO7ADAzICFBwvchwfAvgwCK0BnzrLHzAfGCkyJ0ttAykCK4Qdkd8CMKxLYtc4QILEf4gQRMSbvTrJYTtLoZTjcPQEQzGUzmaJxNLYAA8ABUAHzuUg0ABW1EJnn8TRCsTIsQAcnARPwogB5SkQEyTF5gTnrEAABSZ0DAAE9WeyyZTkU0YC5kO4QiA2ShSDBkIzSCyNfxaY1iMQQgA3TSLKJyilHDksSWeADa6pEAF1lsRgNr3BaGFaAGQB0KS2IQLXIP1W+Qx5AAInJFN5YDjRrBJpiEHiEmwvstEAVJuQumIJeQOTyFm5Sb5vlziYVpQI1VqUBGQA

Answer 1

您可以使用-> https://github.com/microsoft/TypeScript/issues/13923此处提供的DeepReadOnly

示例-> https://www.typescriptlang.org/play?exactOptionalPropertyTypes=true#code/KYDwDg9gTgLgBDAnmYcxQJYFsMwwN1QF44BnGTAOwHM4AfOSgVywCNgp65WIIAbYAENKXJpQAmwAGYZKwcV2Z8+AWABQoSLATJUAEWDAwAJSHiIlPogA8AFQB8cIurhxbcUDGATSaTDjxCOAB+NzgALhcwz29xXwBBKChBG1kpDjgAVUdQgyNTQXNLRETkm2yIqLyTMwsrAHlWACtgAGMYO3t1TWh4WS8oKUFW-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-KRoDgbUjUoQDUABBcwBQk19RjVxv3dOB8BFcs+TQppmwnShEF1F58JZIEc0ojBAW1Wi+HogAyYSTmAIjBPoogZLgAAie9rhgOTyKiSi4Eva8bSkp0eNceF9LdD0vTgUD2iLDkbUU-UWzBfInhsBx-QlMMIygbMgA

注意不要在shouldntWork上设置返回类型，这样Typescript就可以推断出只读的..

export type primitive = string | number | boolean | undefined | null
export type DeepReadonly<T> =
  T extends primitive ? T :
  T extends Array<infer U> ? DeepReadonlyArray<U> :
  DeepReadonlyObject<T>
export interface DeepReadonlyArray<T> extends ReadonlyArray<DeepReadonly<T>> {}
export type DeepReadonlyObject<T> = {
  readonly [P in keyof T]: DeepReadonly<T[P]>
}



interface freeze{
  frozen: boolean;
}

let someFreeze: freeze = {frozen: false}

function shouldntWork() {
  let tester = deepFreeze(someFreeze); 
  return tester;
}

function other()  {
  let something = shouldntWork();
  something.frozen = true;  //Cannot assign to 'frozen' because it is a read-only property.
  console.log(something);
}


function deepFreeze<T>(obj: T):DeepReadonly<T> {
  let propNames = Object.getOwnPropertyNames(obj);
  for (let name of propNames) {
    let value = (obj as any)[name];
    if (value && typeof value === "object") {
      deepFreeze(value);
    }
  }
  return Object.freeze(obj) as DeepReadonly<T>;
}

other();