C#类可以从其接口继承属性吗？

这似乎意味着"不".哪个是不幸的.

[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);
    }
}

类可以从接口继承属性吗？或者我在这里咆哮错误的树？

1> Marc Gravell..：

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不会.无论何时在派生类中实现接口或覆盖成员,都需要重新声明属性.

如果您只关心ComponentModel(不是直接反射),则有一种方法([AttributeProvider])建议来自现有类型的属性(以避免重复),但它仅对属性和索引器使用有效.

举个例子:

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);
        }
    }
}

输出:

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

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@Ryan - 确定:用于描述界面.例如,服务合同.

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嗯.我刚刚注意到问题是从接口继承属性而不是从基类继承属性.

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Marc(和@Rune):是的,OP是关于接口的.但你的答案的第一句可能会令人困惑:"......或派生类中的成员......" - 这不一定是真的.您可以让您的类从其基类继承属性.你只能用接口做到这一点.另见:http://stackoverflow.com/questions/12106566/attribute-on-interface-members-does-not-work

2> tanascius..：

---

您可以定义一个有用的扩展方法......

Type type = typeof(ProjectController);
var attributes = type.GetCustomAttributes( true );

这是扩展方法:

/// 
Searches and returns attributes. The inheritance chain is not used to find the attributes.
/// The type of attribute to search for.
/// The type which is searched for the attributes.
/// Returns all attributes.
public static T[] GetCustomAttributes( this Type type ) where T : Attribute
{
  return GetCustomAttributes( type, typeof( T ), false ).Select( arg => (T)arg ).ToArray();
}

/// 
Searches and returns attributes.
/// The type of attribute to search for.
/// The type which is searched for the attributes.
/// Specifies whether to search this member's inheritance chain to find the attributes. Interfaces will be searched, too.
/// Returns all attributes.
public static T[] GetCustomAttributes( this Type type, bool inherit ) where T : Attribute
{
  return GetCustomAttributes( type, typeof( T ), inherit ).Select( arg => (T)arg ).ToArray();
}

/// 
Private helper for searching attributes.
/// The type which is searched for the attribute.
/// The type of attribute to search for.
/// Specifies whether to search this member's inheritance chain to find the attribute. Interfaces will be searched, too.
/// An array that contains all the custom attributes, or an array with zero elements if no attributes are defined.
private static object[] GetCustomAttributes( Type type, Type attributeType, bool inherit )
{
  if( !inherit )
  {
    return type.GetCustomAttributes( attributeType, false );
  }

  var attributeCollection = new Collection