TypeScript Bot (@typescript-bot) pack this

Heya Ryan Cavanaugh (@RyanCavanaugh), I've started to run the tarball bundle task on this PR at 6f09705. You can monitor the build here.

Hey Ryan Cavanaugh (@RyanCavanaugh), I've packed this into an installable tgz. You can install it for testing by referencing it in your package.json like so:

{
    "devDependencies": {
        "typescript": "https://typescript.visualstudio.com/cf7ac146-d525-443c-b23c-0d58337efebc/_apis/build/builds/93799/artifacts?artifactName=tgz&fileId=3EC3DF89823D37BAFB0102D05E0C5878E1CC64D470DA739FA701667C9C8CEEC602&fileName=/typescript-4.2.0-insiders.20210120.tgz"
    }
}

and then running npm install.

There is also a playground for this build and an npm module you can use via "typescript": "npm:@typescript-deploys/pr-build@4.2.0-pr-42425-2".;

TypeScript Bot (@typescript-bot) pack this

Heya Ryan Cavanaugh (@RyanCavanaugh), I've started to run the tarball bundle task on this PR at d2affa2. You can monitor the build here.

Hey Ryan Cavanaugh (@RyanCavanaugh), I've packed this into an installable tgz. You can install it for testing by referencing it in your package.json like so:

{
    "devDependencies": {
        "typescript": "https://typescript.visualstudio.com/cf7ac146-d525-443c-b23c-0d58337efebc/_apis/build/builds/94491/artifacts?artifactName=tgz&fileId=5D2DE7C1D3D1A47BE543A3A8978BBC0D64E3E7103505294FB8EDC8B577A31AA302&fileName=/typescript-4.2.0-insiders.20210129.tgz"
    }
}

and then running npm install.

There is also a playground for this build and an npm module you can use via "typescript": "npm:@typescript-deploys/pr-build@4.2.0-pr-42425-5".;

This probably also fixes #32821

What milestone will this go into?

TypeScript Bot (@typescript-bot) pack this

Heya Ryan Cavanaugh (@RyanCavanaugh), I've started to run the tarball bundle task on this PR at b7f93bb. You can monitor the build here.

Hey Ryan Cavanaugh (@RyanCavanaugh), I've packed this into an installable tgz. You can install it for testing by referencing it in your package.json like so:

{
    "devDependencies": {
        "typescript": "https://typescript.visualstudio.com/cf7ac146-d525-443c-b23c-0d58337efebc/_apis/build/builds/99188/artifacts?artifactName=tgz&fileId=8A4F5CF4310E72AE3F3599DB677A807009BC386229856DAD4B06C74D77071B7702&fileName=/typescript-4.3.0-insiders.20210325.tgz"
    }
}

and then running npm install.

There is also a playground for this build and an npm module you can use via "typescript": "npm:@typescript-deploys/pr-build@4.3.0-pr-42425-10".;

TypeScript Bot (@typescript-bot) pack this

What's the syntax (if supported) for generic types?

Simplified Example:

type MarkAsString<T extends Record<string, any>> = {
    [K in keyof T]: T extends number ? T[K] /* How to set add a string|number set here? */ : T[K]
}

declare const a: MarkAsString<{ a: boolean, b: number, c: string }>
a.b = '42'; // I want to have this avalible

a.c = '112'

// @ts-expect-error
a.a = '2'

Actual use case

In Vue3 there's Ref<T> (simplified as { value: T}) and Reactive<UnwrappedRef<T>> (unwraps {value: T} to T, recursive)
Basically:

const r = ref({ a: 1} )

r.value.a = 1

const a = reactive(r)
a.a // 1

On a reactive/ref object the set in typescript must be UnwrappedRef<T> which is not true, because when you assign to a reactive it will unwrap the value:

const r = ref({a:1});
const a = ref({
  r
}) // results in `{ r: { a: 1 } }` 

a.r = r; // typescript error  because `r` is `Ref<T>` instead of `UnwrappedRef<T>`, but it works at runtime.

I think what you're actually looking for is how to use the new feature with index signatures. My first guess would have been something like

interface ConvertingRecord {
  get [k: string](): string;
  set [k: string](val: string | number);
}

but that doesn't work on the latest Playground for this build. Maybe it's not currently possible?

Yeah, that's a totally separate and additional feature.

Yeah, that's a totally separate and additional feature.

Cool, should I open an issue?

Sure

This is very cool, is there any information on which version will have this change?

Dmitry Shamshurin (@V1raNi) This has been shipped in 4.3 https://www.typescriptlang.org/docs/handbook/release-notes/typescript-4-3.html#separate-write-types-on-properties

The different type for setter doesn't work for Union type as well. Is this expected? Example can be found here

Wei (@ws93) I didn't see an issue for that yet so I went ahead and opened #45376 .

Dmitry Shamshurin (@V1raNi) This has been shipped in 4.3 https://www.typescriptlang.org/docs/handbook/release-notes/typescript-4-3.html#separate-write-types-on-properties

Oh, thank you very much. It's just I was interested in different visibility and couldn't find it in the text, and the docs seem to be outdated a bit regarding this part.