[API Proposal]: `ActivatorUtilities.CreateFactory<T>` with params span

[alrz]

Background and motivation

The arguments passed to CreateFactory and ObjectFactory are usually of a fixed number so it may be worthwhile to consider params span for both instead of array.

API Proposal

I haven't seen an addition like this so far so I'm not sure about the naming convention.

namespace Microsoft.Extensions.DependencyInjection
{
  public delegate T ObjectFactoryWithParams<out T>(IServiceProvider serviceProvider, params ReadOnlySpan<object?> arguments); 

  public static class ActivatorUtilities
  {
    public static ObjectFactoryWithParams<T> CreateFactory2<T>(params ReadOnlySpan<Type> argumentTypes)
  }
}

API Usage

var factory = ActivatorUtilities.CreateFactory<T>(typeof(SomeType));
var result = factory(serviceProvider, new SomeType());

Alternative Designs

An alternative is to consider making the return type a generic delegate over argument types.

public static ObjectFactory<TArg1, T> CreateFactory<T, TArg1>();
public static ObjectFactory<TArg1, TArg2, T> CreateFactory<T, TArg1, TArg2>();
// etc

public delegate T ObjectFactory<in TArg1, out T>(IServiceProvider serviceProvider, TArg1? arg1);
public delegate T ObjectFactory<in TArg1, in TArg2, out T>(IServiceProvider serviceProvider, TArg1? arg1, TArg2? arg2);
// etc

var factory = ActivatorUtilities.CreateFactory<T, SomeType>();
var result = factory(serviceProvider, new SomeType());

Risks

No response

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[alrz]

@steveharter could this be a candidate for API review alongside #101829?

[steveharter]

@steveharter could this be a candidate for API review alongside #101829?

Yes this is a good proposal; however the window for 9.0 has been closed for such changes.