C#•2y ago

Is there any way to simplify this, or a design pattern I should be following?

public event EventHandler<FizzbuzzDetermineNumberRequest>? DetermineNumberRequestHandlers;
    public event EventHandler<FizzbuzzNumberDeterminedEvent>? NumberDeterminedEventHandlers;
    public event EventHandler<FizzbuzzPrintInfo>? PrintRequestHandlers;
    public event EventHandler<FizzbuzzPrintInfo>? PrintEventHandlers;

    public void RequestDetermineNumber(object? sender, FizzbuzzDetermineNumberRequest? rq)
    {
        DetermineNumberRequestHandlers?.Invoke(sender, rq);
    }

    public void FireNumberDeterminedEvent(object? sender, FizzbuzzNumberDeterminedEvent ev)
    {
        NumberDeterminedEventHandlers?.Invoke(sender, ev);
    }

    public void RequestPrint(object? sender, FizzbuzzPrintInfo rq)
    {
        PrintRequestHandlers?.Invoke(sender, rq);
    }

    public void FirePrintEvent(object? sender, FizzbuzzPrintInfo ev)
    {
        PrintEventHandlers?.Invoke(sender, ev);
    }

public event EventHandler<FizzbuzzDetermineNumberRequest>? DetermineNumberRequestHandlers;
    public event EventHandler<FizzbuzzNumberDeterminedEvent>? NumberDeterminedEventHandlers;
    public event EventHandler<FizzbuzzPrintInfo>? PrintRequestHandlers;
    public event EventHandler<FizzbuzzPrintInfo>? PrintEventHandlers;

    public void RequestDetermineNumber(object? sender, FizzbuzzDetermineNumberRequest? rq)
    {
        DetermineNumberRequestHandlers?.Invoke(sender, rq);
    }

    public void FireNumberDeterminedEvent(object? sender, FizzbuzzNumberDeterminedEvent ev)
    {
        NumberDeterminedEventHandlers?.Invoke(sender, ev);
    }

    public void RequestPrint(object? sender, FizzbuzzPrintInfo rq)
    {
        PrintRequestHandlers?.Invoke(sender, rq);
    }

    public void FirePrintEvent(object? sender, FizzbuzzPrintInfo ev)
    {
        PrintEventHandlers?.Invoke(sender, ev);
    }

11 Replies

DaVinki•2y ago

I'm just trying to have objects outside of the class fire events, but C# only allows invocations from inside of the declaring class

Becquerel•2y ago

this is the best way I know of to fire events inside another class however i'd question if you actually want events if you need to do this consider having public Action<>, Func<>, or straight delegates instead or, use the mediator pattern to take it to another level of abstractness the mediatr nuget package is highly-regarded

DaVinki•2y ago

Do actions and funcs have subscribers like events? I read about some design pattern that isn’t well known called CORE, stands for context objects requests events Everything is a module called upon through requests and events

DaVinki•2y ago

https://hackernoon.com/core-design-pattern-the-way-out-from-overly-complicated-code-b8804449941

CORE design pattern — the way out from overly complicated code | Ha...

Have you ever found yourself stuck in the crazy amount of overly complicated code? No? But you know what it is, right? So let’s suppose you are a developer (at any level of evolution) or you are anyhow involved in product development, then this article is for you! Why? Let’s see the short answer, and then you’re welcome to read more about the so...

DaVinki•2y ago

So if code wants something done, it makes a request in a context and the module receiving those requests does that and makes an event with the results

Becquerel•2y ago

events are identical to actions/funcs under the hood the 'subscriber' to an event is just a method added to the underlying delegate's invocation list so you can do

Action myAction = Method1;
myAction += Method2;
myAction += Method3;

myAction(); // all three methods will run

Action myAction = Method1;
myAction += Method2;
myAction += Method3;

myAction(); // all three methods will run

DaVinki•2y ago

I can make that work Thank you for that

Becquerel•2y ago

i would suggest looking into mediatr, though it seems more like what you are after

DaVinki•2y ago

I will look into everything you’ve told me about, I figured they were just like they were in Java and seemed unfit

Becquerel•2y ago

DaVinki•2y ago

So I tested out Actions and Funcs today, neat stuff and created a bucket sort algorithm using a key extractor function But I have an issue with actions I have this bit of code that I used to test subscribing methods to the invocation

    public static void Main(string[] args)
    {
        var actions = new Action(() => { });
        
        DoSomething.AddGreetingToProgram(actions);
        actions += () => Console.WriteLine(1);
        actions += () => Console.WriteLine(2);
        actions += () => Console.WriteLine(3);
        
        actions.Invoke();
    }

    public static void Main(string[] args)
    {
        var actions = new Action(() => { });
        
        DoSomething.AddGreetingToProgram(actions);
        actions += () => Console.WriteLine(1);
        actions += () => Console.WriteLine(2);
        actions += () => Console.WriteLine(3);
        
        actions.Invoke();
    }

So it prints 1 2 and 3 just fine But when I subscribe something else to the action, it is not run when the action is invoked I did it through another class to see if it's just like events, where you can only subscribe from inside of the declaring class

internal static class DoSomething
{
    public static void AddGreetingToProgram(Action actions)
    {
        void PrintGreetings() => Console.WriteLine("Greetings from static context");
        actions += PrintGreetings;
    }
}

internal static class DoSomething
{
    public static void AddGreetingToProgram(Action actions)
    {
        void PrintGreetings() => Console.WriteLine("Greetings from static context");
        actions += PrintGreetings;
    }
}

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Is there any way to simplify this, or a design pattern I should be following?