rspec/rules/S3908/rule.adoc

Since .Net Framework version 2.0 it is not necessary to declare a delegate that specifies a class derived from ``++System.EventArgs++``. The ``++System.EventHandler<TEventArgs>++`` delegate mechanism should be used instead as it allows any class derived from ``++EventArgs++`` to be used with that handler.


This rule raises an issue when an old style delegate is used as an event handler.


== Noncompliant Code Example

----
public class MyEventArgs : EventArgs
{
}

public delegate void MyEventHandler(object sender, MyEventArgs e); // Noncompliant

public class EventProducer
{
  public event MyEventHandler MyEvent;

  protected virtual void OnMyEvent(MyEventArgs e)
  {
    if (MyEvent != null)
    {
      MyEvent(e);
    }
  }
}

public class EventConsumer
{
  public EventConsumer(EventProducer producer)
  {
      producer.MyEvent += HandleEvent;
  }

  private void HandleEvent(object sender, MyEventArgs e)
  {
    // Do something...
  }
}
----


== Compliant Solution

----
public class MyEventArgs : EventArgs
{
}

public class EventProducer
{
  public event EventHandler<MyEventArgs> MyEvent;

  protected virtual void OnMyEvent(MyEventArgs e)
  {
    if (MyEvent != null)
    {
      MyEvent(e);
    }
  }
}

public class EventConsumer
{
  public EventConsumer(EventProducer producer)
  {
      producer.MyEvent += HandleEvent;
  }

  private void HandleEvent(object sender, MyEventArgs e)
  {
    // Do something...
  }
}
----