Proposal: Improve Native Method Declaration with Source Generators

[Der-Joscha]

First of all, I wanted to thank you for creating this project.

I have a suggestion regarding the usage of unsafe delegate*<...> for declaring native methods. In my opinion, it seems counterintuitive and prone to errors. Specifically:

1. It's not immediately obvious which type parameters are arguments and which is the return type.
2. There's a risk of a careless developer accidentally overwriting the field.
3. Every time the delegate is called, it has to be wrapped in a unsafe { ... } block.

I propose using source generators to generate a thin wrapper method over those delegates. For instance, instead of:

 internal static unsafe delegate*<NativeArray<float>> ArrayReturnIcall;

Users of Coral.Managed could declare their methods like this:

[NativeMethod] 
internal static partial NativeArray<float> ArrayReturnIcall();

The source generator would then kick in at compile time and generate the implementation of the wrapper as well as the delegate.

Here's an example:

namespace Example.Managed
{
    public partial class ExampleClass
    {
        [MethodImpl(MethodImplOptions.AggressiveInlining)]
        internal static partial NativeArray<float> ArrayReturnIcall()
        {
           unsafe { return Delegates.ExampleClass.ArrayReturnIcall(); }
        }
        // other native methods...
    }
}


#pragma warning disable CS0649 // Field is never assigned to, and will always have its default value
namespace Example.Managed.Delegates
{
    [CompilerGenerated]
    public static class ExampleClass
    {
        [CompilerGenerated, DebuggerBrowsable(DebuggerBrowsableState.Never)]
        internal static unsafe delegate*<NativeArray<float>> ArrayReturnIcall;
        // other delegates...
    }
}
#pragma warning restore CS0649 // Field is never assigned to, and will always have its default value

Note that this approach is optional and works in combination with the current implementation. It still allows the use of raw unsafe delegate*<...>.

I'd love to hear your thoughts on this idea, and I'm more than willing to assist with a pull request if you find it promising.

Best regards

[peter1745]

Thanks for the suggestion! Funnily enough I'm working on something like this for calling Corals C# methods from C++, so I could potentially extend the source generator to do what you've suggested, and I probably will end up doing that, although it might not be for a little while 🙂

[Der-Joscha]

Thanks for your reply.
Let me know if you want some help. I have already a basic implementation for that in a personal repository (except referencing the source generator with 'OutputItemType="Analyzer"' when generating the .csproj).