c# - 当泛型事件发生时调用方法

Question

在尝试实现对应在运行时定义的事件触发的方法的调用时，我遇到了问题。我找到了这个答案：

从通用事件处理程序重定向到动态方法

并实现了该解决方案，但是当要调用的方法是实例而不是静态时，我不断收到异常。这是我的部分代码：

public class Operation
{
    public bool EventFired 
    {
        get { return _eventFired; }
    }

    private bool _eventFired = false;

    public void Execute(object source, string EventName)
    {
        EventInfo eventInfo = source.GetType().GetEvent(EventName);
        Delegate handler = null;

        Type delegateHandler = eventInfo.EventHandlerType;
        MethodInfo invokeMethod = delegateHandler.GetMethod("Invoke");
        ParameterInfo[] parms = invokeMethod.GetParameters();

        Type[] parmTypes = new Type[parms.Length];

        for (int i = 0; i < parms.Length; i++)
            parmTypes[i] = parms[i].ParameterType;

        DynamicMethod customMethod = new DynamicMethod
            (
            "TempMethod",
            invokeMethod.ReturnType,
            parmTypes,
            typeof (Operation).Module
            );

        MethodInfo inf = typeof (Operation).GetMethod("SetFlag", BindingFlags.Instance | BindingFlags.Public);

        ILGenerator ilgen = customMethod.GetILGenerator();
        ilgen.Emit(OpCodes.Ldarg_0);
        ilgen.Emit(OpCodes.Call, inf);
        ilgen.Emit(OpCodes.Ret);

        //handler = _customMethod.CreateDelegate(delegateHandler);          // This works if I change SetFlag() to static 

        handler = customMethod.CreateDelegate(delegateHandler, this);       // I get an ArgumentException at this point: 
                                                                            //Cannot bind to the target method because its signature 
                                                                            //or security transparency is not compatible with that of the delegate type.   



        eventInfo.AddEventHandler(source, handler);
    }

    /// <summary>Signals that the event has been raised.</summary>
    public void SetFlag()
    {
        _eventFired = true;
    }

}

我找不到摆脱该异常的方法，如果我将SetFlag()方法设置为静态，则代码可以正常工作，但这不是我需要的。任何建议将不胜感激。提前致谢。

Answer 1

我终于设法通过稍微修改 DynamicMethod 定义来解决问题，如本答案所述：

在动态事件处理程序中引用“this”

如果我将我的类类型添加为Type数组中的第一个值，然后将其作为参数传递给 DynamicMethod，则委托被正确创建并且它适用于实例方法！

public class Operation
{
    public bool EventFired 
    {
        get { return _eventFired; }
    }

    private bool _eventFired = false;

    public void Execute(object source, string EventName)
    {
        EventInfo eventInfo = source.GetType().GetEvent(EventName);
        Delegate handler = null;

        Type delegateHandler = eventInfo.EventHandlerType;
        MethodInfo invokeMethod = delegateHandler.GetMethod("Invoke");
        ParameterInfo[] parms = invokeMethod.GetParameters();

        Type[] parmTypes = new Type[parms.Length + 1];

        parmTypes[0] = this.GetType();  //First parameter is this class type.

        for (int i = 0; i < parms.Length; i++)
            parmTypes[i + 1] = parms[i].ParameterType;

        DynamicMethod customMethod = new DynamicMethod
                                    (
                                        "TempMethod",
                                        invokeMethod.ReturnType,
                                        parmTypes
                                    );

        MethodInfo inf = typeof (Operation).GetMethod("SetFlag", BindingFlags.Instance | BindingFlags.Public);

        ILGenerator ilgen = customMethod.GetILGenerator();
        ilgen.Emit(OpCodes.Ldarg_0);
        ilgen.Emit(OpCodes.Call, inf);
        ilgen.Emit(OpCodes.Ret);

        handler = customMethod.CreateDelegate(delegateHandler, this);      

        eventInfo.AddEventHandler(source, handler);
    }

    /// <summary>Signals that the event has been raised.</summary>
    public void SetFlag()
    {
        _eventFired = true;
    }

}