Welcome to OGeek Q&A Community for programmer and developer-Open, Learning and Share
Welcome To Ask or Share your Answers For Others

Categories

0 votes
565 views
in Technique[技术] by (71.8m points)

c# - Reflection says that interface method are virtual in the implemented type, when they aren't?

I have the following code in an unit test

    public bool TestMethodsOf<T, I>()
  {
   var impl = typeof(T);
   var valid = true;

   foreach (var iface in impl.GetInterfaces().Where(i => typeof(I).IsAssignableFrom(i)))
   {

    var members = iface.GetMethods();

    foreach (var member in members)
    {
     Trace.Write("Checking if method " + iface.Name + "." + member.Name + " is virtual...");
     var implMember = impl.GetMethod(member.Name, member.GetParameters().Select(c => c.ParameterType).ToArray());
     if (!implMember.IsVirtual)
     {
      Trace.WriteLine(string.Format("FAILED"));
      valid = false;
      continue;
     }

     Trace.WriteLine(string.Format("OK"));
    }
   }
   return valid;
  }

which I call by

Assert.IsTrue(TestMethodsOf<MyView, IMyView>());

I want to ensure that all the methods from the interface are declared as virtual. The reason is because I'm applying a spring.net aspect and it will only apply to virtual methods.

The problem I'm having is that implMember.IsVirtual is always true, even when they are not declared as so in the declaring type.

What is wrong with my TestMethodsOf logic?

Cheers

See Question&Answers more detail:os

与恶龙缠斗过久,自身亦成为恶龙;凝视深渊过久,深渊将回以凝视…
Welcome To Ask or Share your Answers For Others

1 Reply

0 votes
by (71.8m points)

All methods declared in an interface are marked as virtual abstract, and all methods that implement interface methods in classes are marked as virtual final, so the CLR knows it can't just call them directly - it has to do vtable lookups at runtime to call the right implementation. The interface implementations are still virtual, but you can't override them as they're final.

As an example, the following C# definition:

public interface IInterface {
    void Method();
}

public class Class : IInterface {
    public void Method() {}
}

compiles to the following IL:

.class public interface abstract IInterface {
    .method public abstract virtual instance void Method() {}
}

.class public Class extends [mscorlib]System.Object implements IInterface {
    .method public specialname rtspecialname instance void .ctor() {}
    .method public virtual final instance void Method() {}
}

与恶龙缠斗过久,自身亦成为恶龙;凝视深渊过久,深渊将回以凝视…
OGeek|极客中国-欢迎来到极客的世界,一个免费开放的程序员编程交流平台!开放,进步,分享!让技术改变生活,让极客改变未来! Welcome to OGeek Q&A Community for programmer and developer-Open, Learning and Share
Click Here to Ask a Question

...