Advice on how best to introduce types to project via fabric

[WhitWaldo]

I've got a project on which I'd like to introduce a class with a method that the developer can use at development-time. The aspect appears to work great, but I'm running into an issue using it alongside a fabric.

Usually, in the fabric, I'd select all the available types and narrow down to those that I want to apply the aspect to. Here though, I simply want to introduce the class to the project, ideally to whatever class contains the entry point (so I can repurpose its namespace so my introduced class is discoverable), but I can't figure out how to set up the fabric to discover this, nor really narrow down the fabric to any single type (e.g. there's no First method available) without specifying a name of it.

The best I've come up with is naming Program as in the following:

amender.SelectMany(c => c.Types)
    .Where(t => t is {TypeKind: TypeKind.Class, Name: "Program"})
    .AddAspectIfEligible(//... );

This works, but is there a better approach I should take instead?

Thanks!

[gfraiteur]

If you want to introduce a top-level class (as opposed to a nested class), you would typically have a compilation-level aspect (IAspect<ICompilation>), so you would just do amender.AddAspect.

[svick]

As for the namespace, you could use the RootNamespace MSBuild property. It's probably already exposed to the compiler/Metalama in your project (if not, add <CompilerVisibleProperty Include="RootNamespace"/> inside an <ItemGroup>in your project file).

Then you can do e.g.:

class Fabric : ProjectFabric
{
    public override void AmendProject(IProjectAmender amender)
    {
        amender.AddAspect(c => new YourCompilationAspect(c.Project.TryGetProperty("RootNamespace", out var ns) ? ns : null));
    }
}

[WhitWaldo]

Excellent, thank you.