C# 4 and .NET 4

Generics features ❘ 113
}
}
}
IEnumerator IEnumerable.GetEnumerator()
{
return GetEnumerator();
}
code snippet LinkedListSample/LinkedList.cs
Using the generic LinkedList < T > , you can instantiate it with an int type, and there ’ s no boxing.
Also, you get a compiler error if you don ’ t pass an int with the method AddLast() . Using the generic
IEnumerable < T > , the foreach statement is also type - safe, and you get a compiler error if that variable in
the foreach statement is not an int :
var list2 = new LinkedList < int > ();
list2.AddLast(1);
list2.AddLast(3);
list2.AddLast(5);
foreach (int i in list2)
{
Console.WriteLine(i);
}
code snippet LinkedListSample/Program.cs
Similarly, you can use the generic LinkedList < T > with a string type and pass strings to the
AddLast() method:
var list3 = new LinkedList < string > ();
list3.AddLast("2");
list3.AddLast("four");
list3.AddLast("foo");
foreach (string s in list3)
{
Console.WriteLine(s);
}
Every class that deals with the object type is a possible candidate for a generic
implementation. Also, if classes make use of hierarchies, generics can be very helpful in
making casting unnecessary.
generiCs feaTures
When creating generic classes, you might need some more C# keywords. For example, it is not possible to
assign null to a generic type. In this case, the keyword default can be used, as demonstrated in the next
section. If the generic type does not require the features of the Object class, but you need to invoke some
specifi c methods in the generic class, you can defi ne constraints.
This section discusses the following topics:
➤
➤
➤
➤
D e f au lt va lu e s
C o n s t r a i nt s
I n h e r it a n c e
S t at i c m e m b e r s
www.it-ebooks.info