//Step 3:
//Method Responsible for Raising Event (Notify registered objects that event occurred)
//by convention protected virtual void (so inheritance is possible, if class is sealed - private, nonvirtual)
protected virtual void OnNewMail(MailEventArgs e)
{
//variant 1
//not thread safe
//if (NewMail != null) NewMail(this, e);
//variant 2
//Thread safe in theory but compiler could optimize it
//EventHandler<MailEventArgs> TempNewMail = NewMail;
//if (TempNewMail != null) TempNewMail(this, e);
//variant 3
//according to Rihter
//EventHandler<MailEventArgs> TempNewMail = Volatile.Read(ref NewMail);
//if (TempNewMail != null) TempNewMail(this, e);
//variant 4
//according to C#6.0 - it is thread safe
NewMail?.Invoke(this, e);
}
private void FaxMsg(Object sender, MailEventArgs e)
{
//'sender' identifies the MailManager object in case we want communicate back to it
Console.WriteLine("FAX received message from {0}, to {1}", e.From, e.To);
}
//Step 4:
//Method that translates the input into the desired event
public void ReceiveEmail(String From, String To)
{
MailEventArgs e = new MailEventArgs(From, To);
OnNewMail(e);
}
private void PcMsg(object sender, MailEventArgs e)
{
Console.WriteLine("PC received message from {0}, to {1}", e.From, e.To);
}