[AttributeUsage(AttributeTargets.Method, AllowMultiple = false)] 
class ArgumentTypeRestrictionAttribute : DecoratorAttributeBase 
{ 
private Type type; 
public ArgumentTypeRestrictionAttribute(Type type) { this.type = type; } 
public override void Intercept(object target) 
{ 
MethodCallMessageWrapper caller = (MethodCallMessageWrapper)target; 
if (caller.ArgCount == 0) return; 
for (int i = 0; i < caller.ArgCount; i++) 
{ 
object arg = caller.Args[i]; 
if ((arg.GetType() != type) && (!arg.GetType().IsAssignableFrom(type))) 
throw new ArgumentException(i.ToString()); 
} 
} 
} 

[AttributeUsage(AttributeTargets.Method, AllowMultiple = false)] 
class ArgumentNotEmptyAttribute : DecoratorAttributeBase 
{ 
public override void Intercept(object target) 
{ 
MethodCallMessageWrapper caller = (MethodCallMessageWrapper)target; 
if(caller.ArgCount == 0) return; 
foreach(object arg in caller.Args) 
if(string.IsNullOrEmpty((string)arg)) 
throw new ArgumentException(); 
} 
} 

class User : MarshalByRefObject 
{ 
private string name; 
private string title; 

[ArgumentTypeRestriction(typeof(string))] // 提供拦截入口 
[ArgumentNotEmpty()] // 提供拦截入口 
public void SetUserInfo(object name, object title) 
{ 
this.name = (string)name; 
this.title = (string)title; 
} 
} 

[TestMethod] 
public void Test() 
{ 
User user = CustomProxy<User>.Create(new User()); 
user.SetUserInfo("joe", "manager"); // 成功 
try 
{ 
user.SetUserInfo(20, "manager"); 
} 
catch (Exception exception) 
{ 
// 因第一个参数类型异常被拦截后抛出异常 
Assert.AreEqual<string>("0", exception.Message); 
} 
try 
{ 
user.SetUserInfo("", "manager"); 
} 
catch (Exception exception) 
{ 
// 因name为空被拦截后抛出异常 
Assert.AreEqual<string>("string is null or empty", exception.Message); 
} 
}