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Clarify usage of IUnionMembers interface #55183

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Clarify usage of IUnionMembers interface #55183

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Update union.md
BarionLP Jul 29, 2026
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Update union.md
BarionLP Jul 29, 2026
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3 changes: 3 additions & 0 deletions docs/csharp/language-reference/builtin-types/union.md
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Expand Up @@ -171,6 +171,9 @@ The compiler prefers `TryGetValue` over the `Value` property when implementing p

### Union member providers

> [!NOTE]
> If an `IUnionMembers` interface is used, all union members must be defined on that interface.

A union type can delegate its union members to a nested `IUnionMembers` interface. When this interface is present, the compiler looks for `Create` factory methods instead of constructors:

:::code language="csharp" source="snippets/unions/MemberProvider.cs" id="MemberProvider":::
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