Missing external aliases

[paulomorgado]

This doc is missing Namespace alias qualifiers.

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Document Details

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• ID: 7569e51d-92c7-294a-2d5f-e1ab3c35fdf8
• Version Independent ID: 86a1c11a-1d3c-902b-6cf3-5c004c59a856
• Content: using directive - C# Reference
• Content Source: docs/csharp/language-reference/keywords/using-directive.md
• Product: dotnet-csharp
• Technology: csharp-language-reference
• GitHub Login: @BillWagner
• Microsoft Alias: wiwagn

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Associated WorkItem - 343933

[BillWagner]

Hi @paulomorgado

The using alias is covered in this section. What do you think is missing? Can you give me a quick example?

[paulomorgado]

@BillWagner,

That's for Using alias directives:

using_alias_directive
    : 'using' identifier '=' namespace_or_type_name ';'
    ;

I'm referring to Namespace alias qualifiers:

qualified_alias_member
    : identifier '::' identifier type_argument_list?
    ;

[BillWagner]

@paulomorgado Thanks for chatting offline, and helping me understand what you're looking for here. I'll summarize:

Imagine a project that references a shared assembly using a qualified alias in each source file:

using MySharedLibrary::Components;

Using the :: syntax instead of . ensures that MySharedLibrary refers to the global namespace MySharedLibrary, not any other nested namespace in scope.

To do the same in a source file, you could write:

global using MySharedLibrary::Components;

But, it's unclear if it's possible to add it to the csproj file using a directive like the following:

<Using Include="MySharedLibrary::Components" />

Ping @dsplaisted for details on the Using Include element.

[dsplaisted]

The code that generates global usings already puts global:: in front of the specified namespace, so I'm not sure whether there's any need for further use of ::. If you specify it in the item then it will be included in the generated code, though I don't know if it's valid to have something like

global using global::MySharedLibrary::Components;

@pranavkm may know more.

[paulomorgado]

It's not valid.

[pranavkm]

We don't currently have a way to specify a different alias identifier. All namespaces are qualified with the global qualifier. We could consider this as an enhancement if you file an issue in https://github.com/dotnet/sdk.

[BillWagner]

Thanks for the discussion.

For this issue (scoped to docs), this article should include a description of the namespace_alias_qualifier used in the example in #26469 (comment)