C#•2y ago

How do delegates work

I have a little problem understanding what type i need to pass a delegate to AddEventHandler because i'm getting the function from reflection and MethodInfo.CreateDelegate tells me i need to pass a type which i don't understand what would that type be for or what derives from a delegate exactly

13 Replies

memw•2y ago

also the delegate must be async since it's a Discord.Net event

foreach (MethodInfo method in cConfig.EventsAssembly.GetTypes().SelectMany(t => t.GetMethods()).Where(m => m.GetCustomAttributes(typeof(EventAttribute), false).Length > 0).ToArray())
        {
            CustomAttributeData catData = method.GetCustomAttributesData().First(a => a.AttributeType.Name == "EventAttribute");
            GetType().GetEvent((string)catData.ConstructorArguments.First().Value!)!.AddEventHandler(this, method.CreateDelegate(typeof(void)));
        }

foreach (MethodInfo method in cConfig.EventsAssembly.GetTypes().SelectMany(t => t.GetMethods()).Where(m => m.GetCustomAttributes(typeof(EventAttribute), false).Length > 0).ToArray())
        {
            CustomAttributeData catData = method.GetCustomAttributesData().First(a => a.AttributeType.Name == "EventAttribute");
            GetType().GetEvent((string)catData.ConstructorArguments.First().Value!)!.AddEventHandler(this, method.CreateDelegate(typeof(void)));
        }

That typeof(void) in there i just put because at this point i tried everything lol, i don't know what type to put in there i mean in this case it should be some type related to any method, so i don't actually know how to do this.

Kouhai•2y ago

You need to declare a delegate that matches your methods' signature method.CreateDelegate<YourDelegate>()

Aaron•2y ago

what is the event you're trying to add to?

memw•2y ago

the event is whatever it gets from the string passed in the attribute constructor arg

Aaron•2y ago

well i'll give an example

memw•2y ago

this is what i don't understand basically

Aaron•2y ago

if you had

public event Func<int, Task> SomeEvent;

public event Func<int, Task> SomeEvent;

typeof(Func<int, Task>) is what you pass to CreateDelegate

memw•2y ago

i see, so that's the function return type then

Aaron•2y ago

its not its return type, thats how you define events Func<T1, TRet> is a delegate type it seems like you have an eventinfo there

Aaron•2y ago

which means you can get that type using https://learn.microsoft.com/en-us/dotnet/api/system.reflection.eventinfo.eventhandlertype?view=net-6.0#system-reflection-eventinfo-eventhandlertype

EventInfo.EventHandlerType Property (System.Reflection)

Gets the Type object of the underlying event-handler delegate associated with this event.

memw•2y ago

so EventInfo.GetType?

Aaron•2y ago

no EventInfo.EventHandlerType you're getting the EventInfo from GetType().GetEvent(...)

memw•2y ago

ok, i'l try to pass (use) that i'l split stuff in variables and pass (use) that, thanks Cannot bind to the target method because its signature is not compatible with t hat of the delegate type. this means that the function the event expects is not compatible as far as i know? @Windows10CE ah it works, it just had to be static, my bad, thanks a lot

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How do delegates work