Fixed an issue with typegen types not being able to provide events that had a union of strings as their type
#3230
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…at had a union of strings as their `type`
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packages/core/package.json
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| "typesVersions": { | ||
| "<4.1": { | ||
| "lib/types.4.1.d.ts": [ | ||
| "types.pre-4.1.d.ts" | ||
| ] | ||
| } | ||
| }, |
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I still need to verify in some external project that this will be resolved correctly
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packages/core/package.json
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| @@ -15,7 +22,8 @@ | |||
| "lib/**/*.js", | |||
| "lib/**/*.d.ts", | |||
| "es/**/*.js", | |||
| "es/**/*.d.ts" | |||
| "es/**/*.d.ts", | |||
| "*.d.ts" | |||
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The plan was to keep types targeting lowe versions of TS in this file and that would have to be published. However, it seems that it's not possible to redirect internal file requests (see here) so this strategy won't work.
To make it happen we would have to bundle all of our types, replace in it what we want, and point to that from typesVersions. It's way more work than what I've wanted to pull off here so I'm going to just revert this part of the change (optimization) and keep it in a TODO comment for v5.
| export type IndexByType<T extends { type: string }> = { | ||
| [K in T['type']]: Extract<T, { type: K }>; | ||
| [K in T['type']]: T extends any ? (K extends T['type'] ? T : never) : never; |
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I wonder why T extends any makes this work 🧐
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https://github.com/statelyai/eng-blog/pull/81/files :P
This is just a way to make this conditional type distributive. Conditional types are distributive when they contain a "naked" type param:
type IsStringDistributive<T> = T extends string ? 1 : 0
// this will run the conditional type over each member of this union type
type Distributes = IsStringDistributive<string | number>
// ^? 1 | 0
type IsStringNonDistributive<T> = [T] extends [string] ? 1 : 0
// this will run the conditional type on the union type "as is"
type DoesntDistribute = IsStringNonDistributive<string | number>
// ^? 0TS playground
TS playground with Omit variants
So this particular type here just checks if the current K extends any of the T['type'] and it will match even if T['type'] is a union. Whereas the previous version would fail because
'FOO' | 'BAR' extends 'FOO' ? 1 : 0 // 0
…at had a union of strings as their `type` (statelyai#3230) * Fixed an issue with typegen types not being able to provide events that had a union of strings as their `type` * Remove `typesVersions` attempt from the core
fixes #3102
why and how? https://github.com/statelyai/eng-blog/pull/81/files