Dictionary expressions: update key-value pair conversions #8850
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CyrusNajmabadi
approved these changes
Dec 8, 2024
| > * If `Eᵢ` is a *key value pair element* `Kᵢ:Vᵢ`, there is an implicit conversion from `Kᵢ` to `K` and an implicit conversion from `Vᵢ` to `V`. | ||
| > * If `Eᵢ` is a *spread element* `..Sᵢ`, then the *iteration type* of `Sᵢ` is `KeyValuePair<Kᵢ:Vᵢ>` and there is an implicit conversion from `Kᵢ` to `K` and an implicit conversion from `Vᵢ` to `V`. | ||
| > * Otherwise there is *no implicit conversion* from the collection expression to the target type. | ||
| An explicit *key-value pair conversion* exists from an expression of type `KeyValuePair<T1, T2>` to a type `KeyValuePair<U1, U2>` |
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Does the explicit conversion matter for us? Or is now for parity/completeness with existing conversions?
Trying to figure out how it would matter for CEs
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The explicit conversion is for completeness and consistency with other conversions.
cston
commented
Dec 12, 2024
proposals/dictionary-expressions.md
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| Key-value pair conversions are similar to *tuple conversions* that allow converting between distinct tuple types. | ||
| That said, a tuple conversion is [*defined*](https://github.com/dotnet/csharpstandard/blob/draft-v8/standard/conversions.md#10213-implicit-tuple-conversions) as a conversion from a *tuple expression* rather than a tuple type, despite being allowed in conversions like `b = a` below, so perhaps conversions between `KeyValuePair<,>` *types* should not be supported. |
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See csharpstandard/issues 1155
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