In this post I looks at how the new single-file .NET run experience is implemented inside the .NET SDK, focusing on how the virtual-project file is built

Andrew Lock's blog focuses on ASP.NET Core development, web APIs, and software architecture. Readers can find tutorials, code samples, and explanations covering topics such as RESTful API design, authentication, and authorization in ASP.NET Core. Additionally, they can learn about dependency injection, middleware, and performance optimization techniques.

.NET Escapades

.NET 10 introduces the ability to run single C# files without a .csproj using `dotnet run app.cs`. Behind the scenes, the SDK creates a virtual project file in memory by parsing #: directives for packages, properties, and SDKs, then uses MSBuild to restore and build the application. The implementation includes caching mechanisms to avoid unnecessary rebuilds and handles various edge cases through target overrides to work around NuGet limitations with in-memory projects.

Behind the scenes of dotnet run app.cs