Add Diff and Spread types
#7
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I just added some contribution guidelines. Would you be able to review them? I'm also interested in feedback if anything there is unclear or could be improved. https://github.com/sindresorhus/type-fest/blob/master/.github/contributing.md |
| @@ -84,3 +84,23 @@ const ab: Merge<Foo, Bar> = {a: 1, b: 2}; | |||
| ``` | |||
| */ | |||
| export type Merge<FirstType, SecondType> = Omit<FirstType, Extract<keyof FirstType, keyof SecondType>> & SecondType; | |||
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| /** | |||
| * Diffs two objects. | |||
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Can you add this to the readme too?
| * | ||
| * @example `type Safe = Diff<AllProperties, UnsafeProperties>` | ||
| */ | ||
| export type Diff<T extends {}, V extends {}> = { |
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Can you use more descriptive type names than T and V? See the other types for inspiration.
| * | ||
| * Given objects with types T and V, returns an object that has all the keys in T that do not also exist in V. | ||
| * | ||
| * @example `type Safe = Diff<AllProperties, UnsafeProperties>` |
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Can you include a more comprehensive example? Should also include the import statement.
| /** | ||
| * Returns a type modeling the result of spreading two objects together. | ||
| * | ||
| * Given objects with types T and V, returns an object that has a type that represents {...T, ...V} |
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How is this different from Merge?
| * Returns a type modeling the result of spreading two objects together. | ||
| * | ||
| * Given objects with types T and V, returns an object that has a type that represents {...T, ...V} | ||
| * @example `const a: Spread<X, Y> = { ...x, ...y }` |
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Doesn't TS already infer the new type correctly from object-spread? Maybe I'm missing the use-case for this type.
sindresorhus
changed the title
Diff<T,V> and Spread<T,V> types
sindresorhus
changed the title
Diff<T,V> and Spread<T,V> typesDiff<T, V> and Spread<T, V> types
sindresorhus
changed the title
Diff<T, V> and Spread<T, V> typesDiff and Spread types
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Ping :) |
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@CvX @BendingBender Do you think these types are something we should add? |
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I prefer to extract types from existing code. I find it difficult to judge if given type will find a use in the future. 😅 Some real-world examples would go a long way. |
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@sindresorhus I'm not sure about this PR. Like @CvX I have difficulties imagining using types like this. They are clever solutons but usually a simpler "dumb" solution is easier to understand and is at the same time obvious for every dev who reads it. I'm sure that these types can be useful, especially in the context of ambient declarations but I have yet to encounter a use case for them. As you've already pointed out, this library is mostly for types that are useful for your projects (#3 (comment)). So what's the point adding types that you can't even imagine to use? |
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I think I have a use case for where this would be helpful. In a ORM I built, I have a few decorators that can potentially be attached for a model, and will automatically populate However, in some models, it doesn't make sense to have either one of those: Omit<T, keyof (Identified & Timestamped)>
&
PartialMaybe<T, Identified>
&
PartialMaybe<T, Timestamped>For context: type PartialMaybe<T, O> = T extends O ? Partial<O> : {};
interface Identified {
id: string;
}
interface Timestamped {
createdAt: firestore.Timestamp;
updatedAt?: firestore.Timestamp;
}So in practice this will conditionally (if they exist) make |
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@sindresorhus My use case for interface returnTypes {
somePropertyToExtend: string
}
function someFunction(): Spread<returnTypes, {
somethingElseThatIsNeeded: string
}>
function anotherFunction(): Spread<returnTypes, {
anotherThingThatIsNeeded: string
}> |
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It would be better to open a new issue to discuss this. |
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