Cometary.Metaprogramming

Cometary.Metaprogramming

This assembly provides the ability to define CompilationEditors that will be used by Cometary to edit the assembly in which they are defined.

Installation

Install-Package Cometary.Metaprogramming

Getting started

Declare a CompilationEditor anywhere in your code.

For example, the following CompilationEditor adds a simple class to the final compilation.

using Cometary;

internal class CustomEditor : CompilationEditor
{
	/// <inheritdoc />
	public override void Initialize(CSharpCompilation _compilation, CancellationToken _cancellationToken)
	{
		RegisterEdit((compilation, cancellationToken) => {
			var tree = SyntaxFactory.ParseSyntaxTree(@"
                namespace Tests {
                    public static class Answers {
                        public static int LifeTheUniverseAndEverything => 42;
                    }
                }
            ");

            return compilation.AddSyntaxTrees(tree);
		});
	}
}

Tell Cometary you'll be metaprogramming your assembly

In any C# file, add the following lines.

using Cometary;

[assembly: EditSelf(typeof(CustomEditor))] // Or whatever your editor is named.

Let the magic be

That's it.

Additional features

The META preprocessor symbol name

You may want some code to only be compiled during the Metaprogramming phase. This can easily be done with the META preprocessor symbol name.

Example

#if META
// Only apply an attribute when editing the declaring assembly.
[assembly: SomeAttribute]
#endif

#if !META
// Only declare a type in the end result.
public class MyClass
{
}
#endif