A New Keyword Overview

new

• new is nothing but an Operator Keyword
• new can be classified into three types.

      They are:

1)      new Operator

2)      new Modifier

3)      new Constraint

• Hides a member inherited from a base class.
• i.e., Derived-Class me replaces the Base-Class.
• We can hide without the use of the new modifier, a warning will be generated.
• If we need to avoid the warning, the new modifier is a must.
• The New Modifier  will hide in  class or struct the following items  from all base class members with the same name

1)      Constant

2)      Field

3)      Property

4)      Method

5)      Indexer

Class BaseClass consists of function Show().

Class DerivedClass hides the function Show()

class Program
    {    
        static void Main(string[] args)
        { 
         Baseclass bc;
         bc = new Baseclass();
         bc.Show();
         Console.ReadLine();
  
        }
   
    }
 
    class Baseclass
    {
        public void Show()
        {
            System.Console.WriteLine("Baseclass::Show");
        }
    }
 
    class DerivedClass : Baseclass
    {
        new public void Show()
        {
            System.Console.WriteLine("DerivedClass::Show");
        }
    }
 

Show() of class BaseClass is executed because the reference variable b refers to the object of class BaseClass.

new Constraint

• Any type argument in a generic class declaration should have a public parameter less constructor.
• Apply the new constraint to a type parameter when the generic class creates new instances of the same type.

class ItemFactory<T> where T
: new()
{
 public T GetNewItem()
 {
return new T();
}
}

public class ItemFactory<T> where T : IComparable, new()
{
}