Delegates - Illustrated C# 2005 - page 349

Parameters
Except in the case of array parameters, the parameter list of an anonymous method must
match that of the delegate in the following three characteristics:

￿ Number of parameters

￿ Types of the parameters

￿Mod iers

You can simplify the parameter list of an anonymous method by leaving the parentheses
empty or omitting them altogether, if both of the following are true:

The delegate's parameter list does not contain any out parameters. ￿

￿ The anonymous method does not use any parameters.

For example, the following code declares a delegate that does not have any out parame-
ters, and an anonymous method that does not use any parameters. Since both conditions are
met, you can omit the parameter list from the anonymous method.

delegate void SomeDel ( int X ); // Declare the delegate type.

SomeDel SDel = delegate // Parameter list omitted
{
PrintMessage();
Cleanup();
};