Microsoft slathers Visual Studio 2019 with extra Docker love, triggers Hot Reload in Preview 2

.NET Core 3.0 Preview 8 – ready for production if you're feeling lucky?

Microsoft continued battering developers with toys as it emitted fresh previews of Visual Studio 2019 and .NET Core 3.

Hot Reloading in Visual Studio

While Microsoft was keen to talk up container tooling in version 16.3 preview 2 of its developer suite, a much-needed improvement to Xamarin.Forms arrived last night in the form of Hot Reload.

XAML Hot Reload for Xamarin.Forms is now available for both the Windows and Mac versions of Visual Studio 2019 (8.3 preview 2 for Mac). It's also one of those things a developer would be forgiven for expecting an IDE like Visual Studio to have done for years. After all, making a form definition change and seeing a preview of it in real time is hardly rocket science, is it?

It would seem it was. In order to see the effect a XAML UI change would have, a developer had to endure an app rebuild.

It was an issue acknowledged at the recent Xamarin Developer Summit, and Pierce Boggan, Microsoft's senior program manager for Mobile Developer Tools, teased developers with XAML Hot Reload. The feature purported to deal with the issue by allowing XAML UI changes to be reflected without building and deploying anything.

Boggan opened up a private preview for the technology a month ago.

Under the Vulture's claw

The Reg took the newly public preview for a spin and found it a considerable time-saver for mobile UI development. Once an app has been compiled, hitting save does indeed show XAML UI changes made in the deployment target rather than having to go through the pain of deploying the thing every time.

It isn't quite as snappy as one might hope – things are going on under the hood to stop typos and the like resulting in a borked app – but it is a considerable improvement on current Visual Studio 2019 functionality.

Upcoming tweaks include incremental reloading (only reload changes), which should address some of our lingering performance worries, and simultaneous reloads for multiple platforms being debugged at the same time.

If Xamarin.Forms development is your thing, we'd have to say XAML Hot Reload makes this update well worth a look by itself. Although keep in mind this release is still very much a preview.

Other than the public preview of Hot Reload, the release also brings Docker Container support to C# projects for serverless Azure Functions (v2). The container tools also make it easier to containerize Azure Functions in a Linux container.

However, more interesting is the ability to debug those Azure Functions inside that Docker container, with stepping through of code and breakpoints present and correct.

Finally, as well as C++ tweaks such IntelliCode being on by default, Mac users finally have a simple way of launching ASP.NET Core projects in browsers other than the macOS default via a configuration selector.

.NET Core 3.0 Preview 8 – creeping closer to release

Microsoft also quietly dropped another preview of .NET Core 3.0, which, as promised, is light on new features as the team focuses on buffing the code to a high sheen ahead of a final release.

The gang is already running the .NET website on .NET Core Preview 8 and insists the code is supported and ready for production. Of course, if you're running Preview 7 (the Release Candidate) then you'll need to upgrade to Preview 8 for that "Go Live" support.

Or perhaps just wait until the thing is actually released with a service pack under its belt before letting it anywhere near a production environment. The Long Term Support (LTS) version will be version 3.1, due in November 2019.

As for 3.0, the team reckons a preview 9 will be coming down the pipe shortly. The roadmap calls for General Availability in September. ®