Alias Any Type in C#12

Question

Alias Any Type in C#12

Shervan360 1,661

Hello,

I want to use the new feature in C#12, but the compiler doesn't know this feature.

Screenshot 2024-08-23 093329

Anonymous

2024-08-23T07:12:18.3433333+00:00
Hi @Shervan360 , Welcome to Microsoft Q&A,

You need to read the version that applies to C# 12.

C# 12 includes the following new features. You can try these features using the latest Visual Studio 2022 version or the .NET 8 SDK.

Alias any type - Introduced in Visual Studio 2022 version 17.6 Preview 3.

Alias any type

You can use the using alias directive to alias any type, not just named types. That means you can create semantic aliases for tuple types, array types, pointer types, or other unsafe types. For more information, see the feature specification. For an example refactoring walkthrough, see Refactor your code using alias any type on the .NET blog.

// This is not legal. // Error CS9132: Using alias cannot be a nullable reference type using X = string?; // This is legal. // The alias is to `List<...>` which is itself not a nullable // reference type itself, even though it contains one as a type argument. using Y = System.Collections.Generic.List<string?>; // This is legal. // This is a nullable *value* type, not a nullable *reference* type. using Z = int?;

Best Regards,

Jiale

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Shervan360 1,661 Reputation points

2024-08-23T08:10:18.14+00:00

Thank you, I have the latest of .NET, VS 2022, and C# 12.
Anonymous

2024-08-23T08:48:37.55+00:00
Anonymous

2024-08-27T09:24:44.5366667+00:00

Is there any update in this issue?

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Anonymous

2024-08-23T07:12:18.3433333+00:00

Hi @Shervan360 , Welcome to Microsoft Q&A,

You need to read the version that applies to C# 12.

C# 12 includes the following new features. You can try these features using the latest Visual Studio 2022 version or the .NET 8 SDK.

Alias any type - Introduced in Visual Studio 2022 version 17.6 Preview 3.

Alias any type

You can use the using alias directive to alias any type, not just named types. That means you can create semantic aliases for tuple types, array types, pointer types, or other unsafe types. For more information, see the feature specification. For an example refactoring walkthrough, see Refactor your code using alias any type on the .NET blog.

// This is not legal. // Error CS9132: Using alias cannot be a nullable reference type using X = string?; // This is legal. // The alias is to `List<...>` which is itself not a nullable // reference type itself, even though it contains one as a type argument. using Y = System.Collections.Generic.List<string?>; // This is legal. // This is a nullable *value* type, not a nullable *reference* type. using Z = int?;

Best Regards,

Jiale

If the answer is the right solution, please click "Accept Answer" and kindly upvote it. If you have extra questions about this answer, please click "Comment".

Note: Please follow the steps in our documentation to enable e-mail notifications if you want to receive the related email notification for this thread.
Shervan360 1,661 Reputation points

2024-08-23T08:10:18.14+00:00

Thank you, I have the latest of .NET, VS 2022, and C# 12.
Anonymous

2024-08-27T09:24:44.5366667+00:00

Is there any update in this issue?

Answer 1

Bruce (SqlWork.com) 78,236 Volunteer Moderator

Your issue is that type alias definitions are not allowed in code blocks. Move the definition to before the class definition.

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Alias Any Type in C#12

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