Sample for Rx Blog - Using Rx to Create more readable timer which stops when no one is listening

RxBlog-TimeStopWhenNoOneCares-Rx.cs

#r "nuget:System.Reactive/5.0.0"
using System.Reactive.Linq;

public class TimeStopWhenNoOneCares
{
    private IObservable<long> _Interval;
    private long _Time;
    
    public IDisposable ObserveTime( Action<long> subscriber )
    {
        if (_Interval == null)
        {
            _Interval = Observable.Create<long>( observer => {
            
                bool stop = false;
            
                Task.Run( ()=>{
                
                    while (!stop)
                    {
                        observer.OnNext(_Time);
                    
                        Task.Delay(1000).Wait();   
                        _Time++;
                    }
                });            
            
                // return function to call when observable was being destroyed
                return ()=> 
                {
                    _Interval = null;
                    stop = true;
                };
            
            }).Replay(1).RefCount(1);
        
        }
    
        return _Interval.Subscribe( subscriber );
    }
}

TimeStopWhenNoOneCares t = new();
var observer = t.ObserveTime( time =>{

    Console.WriteLine( time);

});

Console.ReadLine();

observer.Dispose();

Console.WriteLine( "Time stop" );
Console.ReadLine();

Console.WriteLine( "Time continue from last value" );

t.ObserveTime( time =>{

    Console.WriteLine( time);

});

Console.ReadLine();