C#

Member 2146223 wrote:

please give me a running program ...

Member 2146223 wrote:

i need to create a program ...

static void Main(string[] args)
{
    new Program();
    Console.ReadLine();
}

public Program()
{
    DoIt();
}

public async void DoIt()
{
    AlarmReceived += () => new Task(() => Console.WriteLine("A"));
    AlarmReceived += () => new Task(() => Console.WriteLine("B"));
    await OnAlarm();
}

AlarmReceived += () => Task.Run(() => Console.WriteLine("A"));
AlarmReceived += () => Task.Run(() => Console.WriteLine("B"));

static void Main(string[] args)
{
    new Program();
    Console.ReadLine();
}

public Program()
{
    DoIt2();
    Console.WriteLine("Waiting for alarms to process...");
}

List<Action> alarmActions = new List<Action>();

public void AddAlarm(Action act)
{
    alarmActions.Add(act);
}

public void RemoveAlarm(Action act)
{
    alarmActions.Remove(act);
}

public async void DoIt2()
{
    Console.WriteLine("Adding alarms");
    AddAlarm(() => Alarm1());
    AddAlarm(() => Alarm2());
    await Task.Run(() => ProcessAlarms());
    Console.WriteLine("Removing alarms");
    RemoveAlarm(() => Alarm1());
    RemoveAlarm(() => Alarm2());
    await Task.Run(() => ProcessAlarms());
}

public void ProcessAlarms()
{
    alarmActions.ForEach(a => a());
}

public void Alarm1()
{
    System.Threading.Thread.Sleep(1000);
    Console.WriteLine("Alarm 1");
}

public void Alarm2()
{
    Console.WriteLine("Alarm 2");
}

Action a = () => Alarm1();
Action b = () => Alarm2();
Console.WriteLine("Adding alarms");
AddAlarm(a);
AddAlarm(b);
await Task.Run(() => ProcessAlarms());
Console.WriteLine("Removing alarms");
RemoveAlarm(a);
RemoveAlarm(b);
await Task.Run(() => ProcessAlarms());

Task a = Task.Run(() =>
{
    System.Threading.Thread.Sleep(1000);
    Console.WriteLine("A");
}));

AlarmReceived += () => a;

        public async void DoIt()
        {
            Task a = Task.Run(() =>
            {
                System.Threading.Thread.Sleep(1000);
                Console.WriteLine("A");
            });

<pre>
        Task b = Task.Run(() => Console.WriteLine("B"));

        AlarmReceived += () => a;
        AlarmReceived += () => b;
        Console.WriteLine("Processing alarms");
        await OnAlarm();

        Console.WriteLine("Unwire");
        AlarmReceived -= () => a;
        AlarmReceived -= () => b;
        await OnAlarm();
    }

    internal async Task OnAlarm()
    {
        if (eAlarmReceived == null)
        {
            Console.WriteLine("eAlarmReceived is null!");
            return;
        }

        // REMARK: ToList() to capture the event list at the moment of the call
        var eTasks = eAlarmReceived.GetInvocationList().Cast<Func<Task>>().ToList();

        if (eTasks.Count == 0)
        {
            Console.WriteLine("Nothing to do!");
        }
        else
        {
            Console.WriteLine("Tasks = " + eTasks.Count);
            foreach (var t in eTasks)
                await t();
        }
    }</pre>

Processing alarms
B
Tasks = 2
Waiting for alarms to process...
A
Unwire
Tasks = 2

Marc Clifton wrote:

But again, the use of the anonymous method for AlarmReceived means you can't unwire it.

    class AlarmSource
    {
        public async Task OnAlarm()
        {
            var eTasks = AlarmReceived?.GetInvocationList()?.Cast<Func<Task>>()?.ToList();
            if (eTasks == null)
                return;
            foreach (var t in eTasks)
                await t();
        }
        public event Func<Task> AlarmReceived;
    }

<pre>
class Consumer
{
    public Consumer(string name = null)
    {
        Name = name;
    }
    public string Name { get; set; }

    public AlarmSource Source
    {
        get { return source; }
        set
        {
            Func<Task> handler = () => Task.Run(() => Console.WriteLine(Name));
            if (source != null)
                source.AlarmReceived -= handler;
            source = value;
            if (source != null)
                source.AlarmReceived += handler;
        }
    }
    AlarmSource source;
}

class Program
{
    static void Main(string[] args)
    {
        DoAsyncStuff().Wait();
        Console.ReadLine();
    }
    static async Task DoAsyncStuff()
    {
        var c1 = new Consumer("A");
        var c2 = new Consumer("B");
        var src = new AlarmSource();
        c1.Source = src;
        c2.Source = src;
        await src.OnAlarm();
        c2.Source = null;
        await src.OnAlarm();
    }
}</pre>