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This repository was archived by the owner on Oct 12, 2022. It is now read-only.

The example code in "Generic" does not run #475

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The example code in "Generic" does not run#475
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@FumioNonaka
Fumio Nonaka (FumioNonaka)
opened on Jan 5, 2017

The example code of "Using Type Parameters in Generic Constraints" in "Generic" does not run. The following error is shown.

'Type 'U[keyof U]' is not assignable to type 'T[keyof U]'. Type 'U' is not assignable to type 'T'.'

function copyFields<T extends U, U>(target: T, source: U): T {
	for (let id in source) {
		target[id] = source[id];
	}
	return target;
}
let x = { a: 1, b: 2, c: 3, d: 4 };
copyFields(x, { b: 10, d: 20 });

In fact, this does not run in the Playground.

Activity

  1. mhegazy commented on Jan 5, 2017

    @mhegazy
    Mohamed Hegazy (mhegazy)
    on Jan 5, 2017
    Contributor

    This example is not correct now. It should be typed as:

    function copyFields<T, K extends keyof T>(target: T, source: Pick<T, K>): T {
	for (let id in source) {
		target[id] = source[id];
	}
	return target;
}
  2. Mohamed Hegazy (mhegazy)
    added
    Update
    Accepting PRs
    on Jan 5, 2017

  3. mhegazy commented on Jan 5, 2017

    @mhegazy
    Mohamed Hegazy (mhegazy)
    on Jan 5, 2017
    Contributor

    A PR would be welcomed.

  4. Swap76 commented on Oct 3, 2019

    @Swap76
    Swapnil Satish Shinde (Swap76)
    on Oct 3, 2019
    Contributor

    Hey I am newbie will love to submit a PR

  5. sasurau4 commented on Oct 22, 2019

    @sasurau4
    Daiki Ihara (sasurau4)
    on Oct 22, 2019

    This issue seems fixed by #489

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