InterfaceBaseInvoke.Fody

This is an add-in for Fody which contains a workaround for Interface Default Implementation Base Invocation.
The feature has not been implemented by C# team yet.
The status for it can be seen in dotnet/csharplang#2337

---

• Installation
• Usage
• Example

---

Installation

• Include the Fody and InterfaceBaseInvoke.Fody NuGet packages with a PrivateAssets="all" attribute on their <PackageReference /> items. Installing Fody explicitly is needed to enable weaving.

  <PackageReference Include="Fody" Version="..." PrivateAssets="all" />
  <PackageReference Include="InterfaceBaseInvoke.Fody" Version="..." PrivateAssets="all" />

• If you already have a FodyWeavers.xml file in the root directory of your project, add the <InterfaceBaseInvoke /> tag there. This file will be created on the first build if it doesn't exist:

  <?xml version="1.0" encoding="utf-8" ?>
  <Weavers>
    <InterfaceBaseInvoke />
  </Weavers>

See Fody usage for general guidelines, and Fody Configuration for additional options.

Usage

Call the extension method Base<T> to cast an object to one of its interfaces, and then call a method or a property.
Just like:

• var result = this.Base<Interface>().Method(1, "test");
• var value = this.Base<Interface>().Property

Examples

• An example project

• Unit tests can also serve as examples of API usage. See test cases for valid usage and invalid usage.

• Basic example:

  public interface IService
  {
      int Property => 5;
      void Method() => Console.WriteLine("Calling...");
  }
  
  public class Service : IService
  {
      // call the implementation of interface's property
      public int Property => this.Base<IService>().Property + 1;
  
      public void Method()
      {
          Console.WriteLine("Before call method");
          // call the implementation of interface's method
          this.Base<IService>().Method();
          Console.WriteLine("After call method");
      }
  }