A simple demonstration of a base class constraint. : Base class constaint « Generic « C# / CSharp Tutorial

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C# / CSharp Tutorial » Generic » Base class constaint 
18.19.1.A simple demonstration of a base class constraint.

Because of the base class constraint, all type arguments passed to Test must have A as a base class.

using System; 
 
class 
  public void hello() { 
    Console.WriteLine("Hello")
  

 
class B : A { } 
 
class { } 
 
class Test<T> where T : A 
  T obj; 
 
  public Test(T o) { 
    obj = o; 
  
 
  public void sayHello() { 
    obj.hello()
  

 
class MainClass 
  public static void Main() { 
    A a = new A()
    B b = new B()
    C c = new C()
 
    Test<A> t1 = new Test<A>(a)
 
    t1.sayHello()
 
    Test<B> t2 = new Test<B>(b)
 
    t2.sayHello()
 
 
    // The following is invalid because 
    // C does not inherit A. 
//    Test<C> t3 = new Test<C>(c); // Error! 
  
}
Hello
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18.19.Base class constaint
18.19.1.A simple demonstration of a base class constraint.
18.19.2.A more practical demonstration of a base class constraint
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