Is it possible to store delegates with assigned variables in Lists?

Question

Hello, im working on improving my event system and i stumbled against a problem. I have searched everywhere but i cant seem to find any info. My problem is: I have an AIEvents class which has a ExecuteEvent method in it which subscribes to the OnEvent.AtEvent event, it takes one int parameter. Then i have another class called OnEvent which invokes AtEvent when something happens. My problem is: i want want to have a list of ExecuteEvent with a defined value so when its invoked it executes the ExecuteEvent method with the assigned parameter. Basically i want the ExecuteEvent method to know which OnEvent invokes it and this looks like the best approach to me. If you have any other approaches please share them. Thanks. :)

Edit: I forgot to mention that i cant store the ID (int parameter of ExecuteEvent) in OnEvent.

Comments

You could use an anonymous inline delegate to register the event.
Edit: Or do I miss something?

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Without seeing any code - explaining the problem - it's hard to understand what's actually the problem is. :)

Answer 1

You could design your own event class as following:

    public class EventArgumentPair<T>
    {
        public Action<T> Event;
        public T Argument;

        public EventArgumentPair(Action<T> evt, T arg)
        {
            this.Event = evt;
            this.Argument = arg;
        }
    }

    public class EventList<T>
    {
        private List<EventArgumentPair<T>> delegates = new List<EventArgumentPair<T>>();

        public void Register(Action<T> evt, T arg)
        {
            delegates.Add(new EventArgumentPair<T>(evt, arg));
        }

        public void CallEvents()
        {
            foreach (EventArgumentPair<T> del in delegates)
            {
                // Execute event
                del.Event(del.Argument);
            }
        }
    }

 

This way you have the arguments linked to the specified events/delegates.

Use the class as shown below:

        static EventList<int> events = new EventList<int>();

        static void Main(string[] args)
        {
            events.Register(Print, 7);
            events.Register(Print, 55);
            events.Register(Print, 61);

            events.CallEvents();

            Console.ReadLine();
        }

        static void Print(int i)
        {
            Console.WriteLine("Called: " + i);
        }

 

The code above outputs the following:

Called: 7

Called: 55

Called: 61

 

Let me know if that was your goal.

 

Comments

OK... I admit that's better than some cheap inline delegates.

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Thanks for the fast answer! And yeah, this is exactly what i was looking for. I dont know why i didnt think of that. My system is actually designed very similiarly so i think it will be easy to rework. Have a nice day! :)

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One more question, is it possible to store delegates with assigned parameters at all?

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No. The delegate is just a variable, or more precisely: a pointer to a function. So there's no relation between the actual implementation and it's input/data.