c#传递参数-动态事件订阅
本文关键字：事件 动态 参数 | 更新日期: 2023-09-27 18:05:30
我在控制器中有以下内容，并希望将类型为float的x, y和z传递给订阅者。不过我还是有点跟不上。我需要调整什么来允许我将浮点数(x, y, z)作为参数传递?谢谢你。
private void ProcessEvents()
{
if(Input.GetMouseButtonDown(1))
{
// Data to be passed to subscribers
float x = Input.mousePosition.x;
float y = Input.mousePosition.y;
float z = Input.mousePosition.z;
var publisher = new EventPublisher();
var handler = new Handler();
// Void delegate with one parameter
string eventName = "RightClickEvent";
var rightClickEvent = publisher.GetType().GetEvent(eventName);
rightClickEvent.AddEventHandler(publisher, EventProxy.Create<int>(rightClickEvent, i=>Debug.LogError(i + "!")));
publisher.PublishEvents();
}
}
其他来源:
public class ExampleEventArgs : EventArgs
{
public int IntArg {get; set;}
}
事件发布者:
public class EventPublisher
{
public event EventHandler<ExampleEventArgs> RightClickEvent;
/// <summary>
/// Publishes the events.
/// </summary>
public void PublishEvents()
{
if(RightClickEvent != null)
{
RightClickEvent(this, new ExampleEventArgs{IntArg = 5});
}
}
}
处理程序:
public class Handler
{
public void HandleEventWithArg(int arg) { Debug.LogError("Arg: " + string.Format("[{0}]", arg)); }
}
EventProxy:
static class EventProxy
{
// Void delegate with one parameter
static public Delegate Create<T>(EventInfo evt, Action<T> d)
{
var handlerType = evt.EventHandlerType;
var eventParams = handlerType.GetMethod("Invoke").GetParameters();
//lambda: (object x0, ExampleEventArgs x1) => d(x1.IntArg)
var parameters = eventParams.Select(p=>Expression.Parameter(p.ParameterType,"x")).ToArray();
var arg = getArgExpression(parameters[1], typeof(T));
var body = Expression.Call(Expression.Constant(d),d.GetType().GetMethod("Invoke"), arg);
var lambda = Expression.Lambda(body,parameters);
return Delegate.CreateDelegate(handlerType, lambda.Compile(), "Invoke", false);
}
// Returns an expression that represents an argument to be passed to the delegate
static Expression getArgExpression(ParameterExpression eventArgs, Type handlerArgType)
{
if(eventArgs.Type == typeof(ExampleEventArgs) && handlerArgType == typeof(int))
{
//"x1.IntArg"
var memberInfo = eventArgs.Type.GetMember("IntArg")[0];
return Expression.MakeMemberAccess(eventArgs,memberInfo);
}
throw new NotSupportedException(eventArgs + "->" + handlerArgType);
}
// Void delegates with no parameters
static public Delegate Create(EventInfo evt, Action d)
{
var handlerType = evt.EventHandlerType;
var eventParams = handlerType.GetMethod("Invoke").GetParameters();
//lambda: (object x0, EventArgs x1) => d()
var parameters = eventParams.Select(p=>Expression.Parameter(p.ParameterType,"x"));
var body = Expression.Call(Expression.Constant(d),d.GetType().GetMethod("Invoke"));
var lambda = Expression.Lambda(body,parameters.ToArray());
return Delegate.CreateDelegate(handlerType, lambda.Compile(), "Invoke", false);
}
}
好的，我读了你说的mvc风格的解耦应用模块。我通常喜欢使用强类型代码，即使在使用反射时也是如此，但我对MVC比较陌生，不知道推荐的实践。你比我更了解你的需求，所以我简单地编辑了Nguyen的解决方案，因为我相信他使用了一些未包含在文件中的扩展，并在这里发布了结果。这都是阮的功劳。
namespace Dynamics
{
public static class DynamicHandler
{
/// <summary>
/// Invokes a static delegate using supplied parameters.
/// </summary>
/// <param name="targetType">The type where the delegate belongs to.</param>
/// <param name="delegateName">The field name of the delegate.</param>
/// <param name="parameters">The parameters used to invoke the delegate.</param>
/// <returns>The return value of the invocation.</returns>
public static object InvokeDelegate(this Type targetType, string delegateName, params object[] parameters)
{
return ((Delegate)targetType.GetField(delegateName).GetValue(null)).DynamicInvoke(parameters);
}
/// <summary>
/// Invokes an instance delegate using supplied parameters.
/// </summary>
/// <param name="target">The object where the delegate belongs to.</param>
/// <param name="delegateName">The field name of the delegate.</param>
/// <param name="parameters">The parameters used to invoke the delegate.</param>
/// <returns>The return value of the invocation.</returns>
public static object InvokeDelegate(this object target, string delegateName, params object[] parameters)
{
return ((Delegate)target.GetType().GetField(delegateName).GetValue(target)).DynamicInvoke(parameters);
}
/// <summary>
/// Adds a dynamic handler for a static delegate.
/// </summary>
/// <param name="targetType">The type where the delegate belongs to.</param>
/// <param name="fieldName">The field name of the delegate.</param>
/// <param name="func">The function which will be invoked whenever the delegate is invoked.</param>
/// <returns>The return value of the invocation.</returns>
public static Type AddHandler(this Type targetType, string fieldName,
Func<object[], object> func)
{
return InternalAddHandler(targetType, fieldName, func, null, false);
}
/// <summary>
/// Adds a dynamic handler for an instance delegate.
/// </summary>
/// <param name="target">The object where the delegate belongs to.</param>
/// <param name="fieldName">The field name of the delegate.</param>
/// <param name="func">The function which will be invoked whenever the delegate is invoked.</param>
/// <returns>The return value of the invocation.</returns>
public static Type AddHandler(this object target, string fieldName,
Func<object[], object> func)
{
return InternalAddHandler(target.GetType(), fieldName, func, target, false);
}
/// <summary>
/// Assigns a dynamic handler for a static delegate or event.
/// </summary>
/// <param name="targetType">The type where the delegate or event belongs to.</param>
/// <param name="fieldName">The field name of the delegate or event.</param>
/// <param name="func">The function which will be invoked whenever the delegate or event is fired.</param>
/// <returns>The return value of the invocation.</returns>
public static Type AssignHandler(this Type targetType, string fieldName,
Func<object[], object> func)
{
return InternalAddHandler(targetType, fieldName, func, null, true);
}
/// <summary>
/// Assigns a dynamic handler for a static delegate or event.
/// </summary>
/// <param name="target">The object where the delegate or event belongs to.</param>
/// <param name="fieldName">The field name of the delegate or event.</param>
/// <param name="func">The function which will be invoked whenever the delegate or event is fired.</param>
/// <returns>The return value of the invocation.</returns>
public static Type AssignHandler(this object target, string fieldName, Func<object[], object> func)
{
return InternalAddHandler(target.GetType(), fieldName, func, target, true);
}
private static Type InternalAddHandler(Type targetType, string fieldName,
Func<object[], object> func, object target, bool assignHandler)
{
Type delegateType;
var bindingFlags = BindingFlags.Public | BindingFlags.NonPublic |
(target == null ? BindingFlags.Static : BindingFlags.Instance);
var eventInfo = targetType.GetEvent(fieldName, bindingFlags);
if (eventInfo != null && assignHandler)
throw new ArgumentException("Event can be assigned. Use AddHandler() overloads instead.");
if (eventInfo != null)
{
delegateType = eventInfo.EventHandlerType;
var dynamicHandler = BuildDynamicHandler(delegateType, func);
eventInfo.GetAddMethod(true).Invoke(target, new Object[] { dynamicHandler });
}
else
{
var fieldInfo = targetType.GetField(fieldName);
//,target == null ? BindingFlags.Static : BindingFlags.Instance);
delegateType = fieldInfo.FieldType;
var dynamicHandler = BuildDynamicHandler(delegateType, func);
var field = assignHandler ? null : target == null
? (Delegate)fieldInfo.GetValue(null)
: (Delegate)fieldInfo.GetValue(target);
field = field == null
? dynamicHandler
: Delegate.Combine(field, dynamicHandler);
if (target != null)
target.GetType().GetField(fieldName).SetValue(target, field);
else
targetType.GetField(fieldName).SetValue(null, field);
//(target ?? targetType).SetFieldValue(fieldName, field);
}
return delegateType;
}
/// <summary>
/// Dynamically generates code for a method whose can be used to handle a delegate of type
/// <paramref name="delegateType"/>. The generated method will forward the call to the
/// supplied <paramref name="func"/>.
/// </summary>
/// <param name="delegateType">The delegate type whose dynamic handler is to be built.</param>
/// <param name="func">The function which will be forwarded the call whenever the generated
/// handler is invoked.</param>
/// <returns></returns>
public static Delegate BuildDynamicHandler(this Type delegateType, Func<object[], object> func)
{
var invokeMethod = delegateType.GetMethod("Invoke");
var parameters = invokeMethod.GetParameters().Select(parm =>
Expression.Parameter(parm.ParameterType, parm.Name)).ToArray();
var instance = func.Target == null ? null : Expression.Constant(func.Target);
var convertedParameters = parameters.Select(parm => Expression.Convert(parm, typeof(object))).Cast<Expression>().ToArray();
var call = Expression.Call(instance, func.Method, Expression.NewArrayInit(typeof(object), convertedParameters));
var body = invokeMethod.ReturnType == typeof(void)
? (Expression)call
: Expression.Convert(call, invokeMethod.ReturnType);
var expr = Expression.Lambda(delegateType, body, parameters);
return expr.Compile();
}
}
}
并且我还添加了一些代码来测试方法，当我分配回调委托时，我可以使用简单的lambdas，但我更愿意使用"return true"定义，因为我设置了断点来检查函数是否被实际调用。
class TestClass
{
private void Test()
{
TestInstance();
TestStatic();
}
private void TestInstance()
{
var eventClass = new EventClass();
eventClass.InvokeDelegate("InstanceEventRaiseDelegate");
eventClass.AddHandler("InstanceEvent", parameters =>
{
return true;
});
eventClass.AddHandler("InstanceEventRaiseDelegate", parameters =>
{
return true;
});
eventClass.InvokeDelegate("InstanceEventRaiseDelegate");
eventClass.AssignHandler("InstanceEventRaiseDelegate", parameters =>
{
return true;
});
eventClass.InvokeDelegate("InstanceEventRaiseDelegate");
}
private void TestStatic()
{
typeof(EventClass).InvokeDelegate("StaticEventRaiseDelegate");
typeof(EventClass).AddHandler("StaticEvent", parameters =>
{
return true;
});
typeof(EventClass).AddHandler("StaticEventRaiseDelegate", parameters =>
{
return true;
});
typeof(EventClass).InvokeDelegate("StaticEventRaiseDelegate");
typeof(EventClass).AssignHandler("StaticEventRaiseDelegate", parameters =>
{
return true;
});
typeof(EventClass).InvokeDelegate("StaticEventRaiseDelegate");
}
public class EventClass
{
#region Instance
public EventClass()
{
InstanceEventRaiseDelegate = OnInstanceEvent;
}
public Action InstanceEventRaiseDelegate;
public event EventHandler InstanceEvent;
public void OnInstanceEvent()
{
if (InstanceEvent != null)
InstanceEvent(this, EventArgs.Empty);
}
#endregion
#region Static
static EventClass()
{
StaticEventRaiseDelegate = OnStaticEvent;
}
public static Action StaticEventRaiseDelegate;
public static event EventHandler StaticEvent;
public static void OnStaticEvent()
{
if (StaticEvent != null)
StaticEvent(null, EventArgs.Empty);
}
#endregion
}
}
很抱歉回复晚了，但似乎你能在其他地方找到解决方案:)，祝你好运。
我已经添加了一些代码，将实现您所需要的:
我将getArgExpression函数修改为如下
// Returns a List of expressions that represent the arguments to be passed to the delegate
static IEnumerable<Expression> getArgExpression(ParameterExpression eventArgs, Type handlerArgType)
{
if (eventArgs.Type == typeof(ExampleEventArgs) && handlerArgType == typeof(int))
{
//"x1.IntArg"
var memberInfo = eventArgs.Type.GetMember("IntArg")[0];
return new List<Expression> { Expression.MakeMemberAccess(eventArgs, memberInfo) };
}
if (eventArgs.Type == typeof(MousePositionEventArgs) && handlerArgType == typeof(float))
{
//"x1.X"
var xMemberInfo = eventArgs.Type.GetMember("X")[0];
//"x1.Y"
var yMemberInfo = eventArgs.Type.GetMember("Y")[0];
//"x1.Z"
var zMemberInfo = eventArgs.Type.GetMember("Z")[0];
return new List<Expression>
{
Expression.MakeMemberAccess(eventArgs, xMemberInfo),
Expression.MakeMemberAccess(eventArgs, yMemberInfo),
Expression.MakeMemberAccess(eventArgs, zMemberInfo),
};
}
throw new NotSupportedException(eventArgs + "->" + handlerArgType);
}
调用函数保持不变，因为它对IEnumerable<Expression>有过载。然后我添加了EventArgs特定于你的MousePosition情况
public class MousePositionEventArgs : EventArgs
{
public float X { get; set; }
public float Y { get; set; }
public float Z { get; set; }
}
进一步，我在'EventProxy'中写了一个新函数，它将处理具有3个相同类型参数的委托
// Void delegate with three parameters
static public Delegate Create<T>(EventInfo eventInformation, Action<T, T, T> lambdaDelegate)
{
var handlerType = eventInformation.EventHandlerType;
var eventParams = handlerType.GetMethod("Invoke").GetParameters();
//lambda: (object x0, ExampleEventArgs x1) => d(x1.X,x1.Y,x1.Z)
var parameters = eventParams.Select(p => Expression.Parameter(p.ParameterType, "x")).ToArray();
var arg = getArgExpression(parameters[1], typeof(T));
var body = Expression.Call(Expression.Constant(lambdaDelegate), lambdaDelegate.GetType().GetMethod("Invoke"), arg);
var lambda = Expression.Lambda(body, parameters);
return Delegate.CreateDelegate(handlerType, lambda.Compile(), "Invoke", false);
}
现在我们可以使用以下代码轻松地添加MouseEvent订阅
rightClickEvent.AddEventHandler(publisher, EventProxy.Create<float>(rightClickEvent, (t, u, v) => Console.Write(t + "x" + u + "x" + v + "!")));
if (Type == typeof(...))。
我要花更多的时间来制定解决方案，但如果你真的感兴趣，我可以试着写下来，并张贴。