Can a C# class inherit attributes from its interface?

attributes, c#

Solution

No. Whenever implementing an interface or overriding members in a derived class, you need to re-declare the attributes.

If you only care about ComponentModel (not direct reflection), there is a way (`[AttributeProvider]`) of suggesting attributes from an existing type (to avoid duplication), but it is only valid for property and indexer usage.

As an example:

using System;
using System.ComponentModel;
class Foo {
    [AttributeProvider(typeof(IListSource))]
    public object Bar { get; set; }

    static void Main() {
        var bar = TypeDescriptor.GetProperties(typeof(Foo))["Bar"];
        foreach (Attribute attrib in bar.Attributes) {
            Console.WriteLine(attrib);
        }
    }
}

outputs:

System.SerializableAttribute
System.ComponentModel.AttributeProviderAttribute
System.ComponentModel.EditorAttribute
System.Runtime.InteropServices.ComVisibleAttribute
System.Runtime.InteropServices.ClassInterfaceAttribute
System.ComponentModel.TypeConverterAttribute
System.ComponentModel.MergablePropertyAttribute

Problem

This would appear to imply "no". Which is unfortunate. ``` [AttributeUsage(AttributeTargets.Interface | AttributeTargets.Class, AllowMultiple = true, Inherited = true)] public class CustomDescriptionAttribute : Attribute { public string Description { get; private set; } public CustomDescriptionAttribute(string description) { Description = description; } } [CustomDescription("IProjectController")] public interface IProjectController { void Create(string projectName); } internal class ProjectController : IProjectController { public void Create(string projectName) { } } [TestFixture] public class CustomDescriptionAttributeTests { [Test] public void ProjectController_ShouldHaveCustomDescriptionAttribute() { Type type = typeof(ProjectController); object[] attributes = type.GetCustomAttributes( typeof(CustomDescriptionAttribute), true); // NUnit.Framework.AssertionException: Expected: 1 But was: 0 Assert.AreEqual(1, attributes.Length); } } ``` Can a class inherit attributes from an interface? Or am I barking up the wrong tree here?

Original source

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