C# 0 The Complete Reference

ISeries

 interface must be passed to 

ByTwos

. Otherwise, 

there is no way for the interface to receive the type argument.

Next, the current value of the series, 

val

, and the starting value, 

start

, are declared to be 

objects of the generic type 

T

. Then, a delegate called 

IncByTwo

 is declared. This delegate 

defines the form of a method that will be used to increase an object of type 

T

 by two. In order 

for

ByTwos

 to work with any type of data, there must be some way to define what an increase 

by two means for each type of data. This is achieved by passing to the 

ByTwos

 constructor a 

reference to a method that performs an increase by two. This reference is stored in 

incr

. When 

the next element in the series is needed, that method is called through the 

incr

 delegate to 

obtain the next value in the series.

Notice the class 

ThreeD

. It encapsulates three-dimensional (X,Z,Y) coordinates. It is 

used to demonstrate 

ByTwos

 on a class type.

In

GenIntfDemo

, three increment methods are declared; one for