Work with Signals

What you should know beforehand:

Lifetime

Examples (?):

SignalEmitter.cs
SignalListener.cs
SolutionStateTracker.cs - more complex example of using signals

Signal is a way for a class to provide notifications. Signals are very similar to C# events, nevertheless, there are differences that make them more suitable for use within ReSharper data flow infrastructure.

public class SignalEmitter
{
    public ISignal<bool> SomethingHappened { get; }
 
    public SignalEmitter(Lifetime lifetime)
    {
        SomethingHappened = new Signal<bool>(lifetime, "SignalEmitter.SomethingHappened");
    }
 
    public void MakeItHappen(bool arg)
    {
        SomethingHappened.Fire(arg);
    }

}
 
 
public class SignalListener
{
    public SignalListener(Lifetime lifetime, SignalEmitter signalEmitter)
    {
        signalEmitter.SomethingHappened.Advise(lifetime, arg => MessageBox.ShowInfo($"Something happened and it's {arg}"));
    }
}

Notes

Signals must implement the ISignal interface.
To "subscribe" a handler to a signal, use the Advise method. A signal allows any number of listeners.
Unlike C# events, you should not care about "unsubscribing" from a signal to prevent memory leak. When you "subscribe" to a signal via Advise, you also pass a lifetime. Once the lifetime is terminated, ReSharper will take care about "unsubscribing" by itself.
To fire the signal, use the Fire method.
Signals have much in common with IProperty.
Signals are perfectly suited for MVC concept when an event should be fired by a view.
In simple cases, when you need a signal only for notification purposes (with no payload), you can use the ISimpleSignal interface.

Last modified: 20 April 2023