Wrapper for a method that accepts (EventArgs)
题
I'm trying to implement EventArgs to pass a list of parameters to my messaging system: Question.
I subclassed EventArgs:
public class SingleParameterArgs<T> : EventArgs
{
public T arg1;
public SingleParameterArgs(T _arg1)
{
arg1 = _arg1;
}
}
Here's the class and method that should accept the EventArgs:
static public class Messenger<TEventArgs> where TEventArgs : EventArgs {
private static Dictionary< string, EventHandler<TEventArgs> > eventTable = new Dictionary< string, EventHandler<TEventArgs> >();
static public void Invoke(string eventType, TEventArgs args) {
EventHandler<TEventArgs> eventHandler;
if (eventTable.TryGetValue(eventType, out eventHandler)) {
if (eventHandler != null)
eventHandler();
}
}
}
Before implementing EventArgs I would invoke a message in the following way:
Messenger<GameEndingType>.Invoke( "end game", GameEndingType.TimeEnded );
But now it looks much longer and much more complicated:
Messenger< SingleParameterArgs<GameEndingType> >.Invoke( "end game", new SingleParameterArgs<GameEndingType>(GameEndingType.TimeEnded) );
Is it possible to make it look shorter? I don't want to type such a long line every time I need to send a message. Maybe I could create a wrapper? Something like this would be perfect: Messenger.Invoke("end game", GameEndingType.TimeEnded);
What is the best way to create a uniform wrapper for a random amount of parameters?
解决方案
Are you happy for your Messenger
class to be tied to SingleParameterArgs<T>
? If so, you could use:
// Here TEventArgs represents the element type *within* SingleParameterArgs
public static class Messenger<TEventArgs> {
private static
Dictionary<string, EventHandler<SingleParameterArgs<TEventArgs>> eventTable =
new Dictionary<string, EventHandler<SingleParameterArgs<TEventArgs>>();
public static void Invoke(string eventType, TEventArgs args) {
EventHandler<SingleParameterArgs<TEventArgs>> eventHandler;
if (eventTable.TryGetValue(eventType, out eventHandler)) {
if (eventHandler != null) {
eventHandler();
}
}
}
}
Of course you can have both, with a totally general Messenger
class (as per your question), and then a SingleParameterMessenger
class which delegates to it:
public static class SingleParameterMessenger<TEventArgs> {
public static void Invoke(string eventType, TEventArgs args) {
Messenger<SingleParameterArgs<TEventArgs>>.Invoke(eventType, args);
}
}
Just as an aside, I'm not really sure this is all a good idea anyway - particularly in terms of static registration, which tends to make testing harder, and certainly needs more care in terms of concurrency. (Your code is currently not threadsafe.)