A simple demonstration of a base class constraint. : Base class constaint : Generic C# Examples

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




    
using  System;  
  
class  A  {  
    public  void  hello()  {  
        Console.WriteLine("Hello");  
    }  
}  
  
class  B  :  A  {  }  
  
class  C  {  }  
  
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!  
    }  
}