How to Handle net6.0-only Code

[TheCodeTraveler]

Question

What is the best way to add support for net6.0-only code?

Current Setup

In CommunityToolkit.Maui.csproj and CommunityToolkit.Maui.Core.csproj, we specify specific behavior for the following file types:

• *.shared.cs
• *.ios.cs
• *.macos.cs
• *.macios.cs
• *.android.cs
• *.windows.cs

The platform-specific files only compile + run on that specific platform (with the exception of macios which runs on both iOS + MacCatalyst), and the *.shared.cs files compile + run on each platform.

Problem

The current setup leaves us without an option for code that only runs on net6.0 (ie not a platform like net6.0-ios or net6.0-android), aka net6.0-only code.

Currently, we handle net6.0-only code by using the following ifdef in a *.shared.cs file:

#if !(IOS || ANDROID || MACCATALYST || WINDOWS)
  // net6.0 code
#endif

Here is an example from Snackbar.shared.cs:

Maui/src/CommunityToolkit.Maui/Alerts/Snackbar/SnackBar.shared.cs

Lines 103 to 123 in 2fba2f4

	#if !(IOS || ANDROID || MACCATALYST || WINDOWS)
	/// <inheritdoc/>
	private partial Task ShowNative(CancellationToken token)
	{
	token.ThrowIfCancellationRequested();
	OnShown();
	return Task.CompletedTask;
	}
	/// <inheritdoc/>
	private partial Task DismissNative(CancellationToken token)
	{
	token.ThrowIfCancellationRequested();
	OnDismissed();
	return Task.CompletedTask;
	}
	#endif

[TheCodeTraveler]

Proposal

I propose that, in CommunityToolkit.Maui.csproj and CommunityToolkit.Maui.Core.csproj, we add one more file type:

• *.net.cs

  <ItemGroup Condition="$(TargetFramework.StartsWith('net')) != true AND '$(TargetFramework)' != 'net6.0'">
    <Compile Remove="**\*.net" />
    <None Include="**\*.net" Exclude="$(DefaultItemExcludes);$(DefaultExcludesInProjectFolder)" />
    <Compile Remove="**\net\**\*.cs" />
    <None Include="**\net\**\*.cs" Exclude="$(DefaultItemExcludes);$(DefaultExcludesInProjectFolder)" />
  </ItemGroup>

This would then allow us to create partial classes for net6.0-only code, e.g. Snackbar.net.cs.

Unknowns / Concerns

Before implementing this, I have one major concern:

How will this affect .NET MAUI apps that don't use a single project + multi-targeting?

If a .NET MAUI app has a net6.0 project where they write all of their cross-platform .NET MAUI code (similar to how we use .NET Standard for Xamarin.Forms apps), will the net6.0 project defer to the *.android.cs file when compiled + run? Or will it compile + run the *.net.cs code instead?

If the *.net.cs code is chosen, it will throw errors such as NotImplementedException when the PopupViewHandler runs CreateNativeElement()

This likely won't be a common scenario, but it is a valid .NET architecture that we should take into account to avoid future problems.

[VladislavAntonyuk]

maybe we can do it with Constants?

<PropertyGroup Condition="$(TargetFramework)==(IOS || ANDROID || MACCATALYST || WINDOWS)">
  <DefineConstants>Platofrms</DefineConstants>
</PropertyGroup>

[maxkoshevoi]

+1 for just manually defining some new symbol. For now consensus is probably on NET_ANY
Here's another possible solution for this: dotnet/sdk#22788 (comment)

will the net6.0 project defer to the *.android.cs file when compiled + run?

Interesting question. From my understanding of MSBuild both approaches (#if or *.net.cs) should work the same, since both of them simply exclude/include some code from being compiled.

[pictos]

Don't like the idea of having just one way to handle that. #if are really good when you have just a small portion of code that will run on only .net6 or in a specific scenario. But for most scenarios #if will make the code hard to read and maintain, so having a file for that will be the best. We can take as reference projects like Xamarin.Essentials and .NET MAUI, they use a file to handle netstandard (aka .net6) files and they succeed.

[VladislavAntonyuk]

Agree with @pictos.
For the Snackbar example I would prefer #if. As for the big changes like in Popup I would go with *.net.cs

[maxkoshevoi]

We can take as reference projects like Xamarin.Essentials and .NET MAUI, they use a file to handle netstandard (aka .net6) files and they succeed.

If they are doing it, then Toolkit should follow to keep style consistent.

I was coming from an idea that net code is usually pretty minimal (couple of lines), and maybe there's no need to a separate file in most cases (and short #if will do). But if there are more then two-three lines of code, separate file makes sense.

[VladislavAntonyuk]

I believe this one is resolved by #576

[CliffAgius]

Closed as answered