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該任務是在運行時創建事件處理程序。我需要用不同事件的不同參數值調用這個方法。事件和它們的編號只在運行時才知道。所以我試圖生成動態方法,每個方法都會分配給某個事件,但通常它們只是將一些值傳遞給實例方法並調用它。如何在訂閱事件時傳遞值並在事件觸發時獲取它(DynamicMethod使用問題)
如果類似的事情能夠以更簡單的方式完成,那將會很棒。我的意思是在訂閱階段傳遞一些價值,然後在事件觸發時獲得它。
這就是我想現在要做的:
public class EventSource
{
public event EventHandler eventOne;
public event EventHandler eventTwO;
public event EventHandler eventThree;
}
public class EventListener
{
SubscribeForEvents()
{
BindingFlags flags =
BindingFlags.IgnoreCase |
BindingFlags.Public |
BindingFlags.Instance;
// Suppose we've already got EventInfo
// and target source somewhere
// so we can do eventInfo.AddEventHandler(target, delegate)
// Now we need a delegate.
int value = 42;
Type tDelegate = eventInfo.EventHandlerType;
// http://msdn.microsoft.com/en-us/library/ms228976(VS.95).aspx
Type returnType = GetDelegateReturnType(tDelegate);
DynamicMethod listener = new DynamicMethod("", null,
GetDelegateParameterTypes(tDelegate), this.GetType());
/////////
Type[] callParameters = { typeof(int) };
MethodInfo method = this.GetType().GetMethod("ToCallFromDelegate", flags);
ILGenerator generator = listener.GetILGenerator();
// No success in this mess. What's wrong?
generator.Emit(OpCodes.Ldc_I4, value);
generator.Emit(OpCodes.Call, method);
generator.Emit(OpCodes.Pop);
generator.Emit(OpCodes.Ret);
/////////////
Delegate delegate = listener.CreateDelegate(tDelegate);
eventInfo.AddEventHandler(target, delegate);
// When triggered, there is InvalidProgramException
}
void ToCallFromDelegate(int value)
{
doSomething();
}
}