.NET 10 Preview 3 bolsters standard library, C#, WebAssembly

Microsoft has released its third preview of.NET 10, a planned update to the company’s cross-platform, open-source, application development platform. Among the highlights,.NET 10 Preview 3 introduces an AOT-safe constructor for ValidationContext, more powerful C# language extensions, and Blazor WebAssembly improvements..NET 10 Preview 3 was unveiled April 10 and can be downloaded from dotnet.microsoft.com. It follows Preview 2, published March 18, and Preview 1, published February 25. .NET 10 is likely to ship as a production release in November.

Among the capabilities in third preview is an AOT-safe constructor for the ValidationContext class in the standard library. The ValidationContext class is used during options validation to provide validation context. However, because extracting the DisplayName can involve reflection, existing constructors of ValidationContext are currently marked as unsafe for AOT (ahead of time) compilation. The new constructor ensures AOT safety, enabling developers to use ValidationContextin native builds without bumping into errors or warnings.

Also with.NET 10 Preview 3, the standard library gains a deterministic option for the LightGBM trainer in ML.NET. This update exposes LightGBM’s deterministic, force_row_wise, and force_cos_wise options to allow developers to force deterministic training behavior when needed. And for C# 14, extensions now support static methods, instance properties, and static properties. More extension support is planned for an upcoming release, Microsoft said.

Other enhancements in.NET 10 Preview 3:

Standalone Blazor WebAssembly apps now can reference static web assets using either a generated import map or a fingerprinted URL. Also in Blazor WebAssembly, response streaming is now enabled by default for HttpClient. This improves performance and reduces memory usage when handling large responses, Microsoft said.

In the.NET runtime, improved code layout is featured via the JIT compiler, with an optimization related to block ordering.

With the SDK and CLI, the --interactive flag will be enabled by default for all uses of the CLI believed to be interactive, specifically those where the command output has not been redirected, as well as those that are not running in an environment believed to be a CI/CD server.

For.NET MAUI (Multi-platform App UI), various performance improvements have been made. Also, a CancellationToken now may be passed to WebAuthenticator.AuthenticateAsync, enabling programmatic canceling of authentication.

OpenAPI support has been enabled by default in the ASP.NET Core Web API (native AOT) template.

On.NET for Android, the release focused on quality improvements, experimental runtimes, and build performance..NET 10 Preview 2 offered improvements such as allowing callers to choose which encryption and digest algorithms are used to produce the output..NET 10 Preview 1 introduced C# 14, with “first-class” support for System.Span and System.ReadOnlySpan in the language.