using System;

using OpenQA.Selenium;

using System.Collections;

using System.Collections.Generic;

using OpenQA.Selenium.Support;

​

​

public class Program{

  static void Main() {

  //  A a = new A(425);

    B b = new B(123);

    C c = new C();

​

    // The following is valid because A is the specified base class.

   // Test<A> t1 = new Test<A>(a);

​

  //  t1.SayHello();

​

    // The following is valid because B inherits A.

    Test<B> t2 = new Test<B>(b);

    t2.SayHello();

    Console.WriteLine(b._Ax);

    // The following is invalid because C does not inherit A.

//    Test<C> t3 = new Test<C>(c); // Error!

//    t3.SayHello(); // Error!

  }

}

// A simple demonstration of a base class constraint.

//using System;/* w   w w   .d   e m   o  2  s .  c    o  m*/

​

public class A {

    protected int _x {get; set;}

​

    protected A(int x){

        _x = x;

    }

  public void Hello() {

    Console.WriteLine("Hello");

  }

}

​

// Class B inherits A.

public class B : A {

​

public int _Ax => this._x;

    public B(int x) : base(x)

    {

        _x = x;

    }

​

}

​

// Class C does not inherit A.

class C { }

​

// Because of the base class constraint, all type arguments

// passed to Test must have A as a base class.

class Test<T> where T : A {

  T obj;

​

  public Test(T o) {

    obj = o;

  }

​

​

  public void SayHello() {

    // OK to call Hello() because it's declared

    // by the base class A.

    obj.Hello();

​

  }

}

​