将委托作为属性传递

Question

我正在尝试使用 this 方法将委托作为参数传递。

public delegate Guid SpaceIdGetter();
public class SpaceIdAttribute : Attribute
    {
        public SpaceIdGetter spaceGetter { get; set; }

        public SpaceIdAttribute(Type delegateType, string delegateName)
        {
            spaceGetter = (SpaceIdGetter)Delegate.CreateDelegate(delegateType, delegateType.GetMethod(delegateName));
        }
    }

    public static class ContextInfo
    {
        public static SpaceIdGetter GetSpaceId()
        {
            return new SpaceIdGetter( () =>
                    {
                        return Guid.Empty;
                    }
                );
        }
    }

当我尝试使用反射创建委托时出现错误

spaceGetter = (SpaceIdGetter)Delegate.CreateDelegate(delegateType, delegateType.GetMethod(delegateName));

Type must derive from Delegate.

编辑：这是我的使用方式

[SpaceId(typeof(ContextInfo), "GetSpaceId")]
public virtual string Body { get; set; }

Answer 1

ContextInfo 不是委托，Delegate.CreateDelegate 必须接受委托。尝试： spaceGetter = (SpaceIdGetter)Delegate.CreateDelegate(typeof(Action<Guid>), delegateType.GetMethod(delegateName));

Answer 2

ContextInfo 实际上是一个已经创建委托类型的工厂 - 所以不需要通过反射创建委托 - 你只需要通过反射调用工厂:

public SpaceIdAttribute(Type delegateType, string delegateName)
{
  var factoryMethod = delegateType.GetMethod(delegateName);
  spaceGetter = (SpaceIdGetter)factoryMethod.Invoke(null, null);
}

将委托作为属性传递

Passing a delegate as an Attribute

c#

delegates