private static void Main(string[] args)
{
/*
* In this example we have a simple decorator which extends StringBuilder
* type of .Net and add it the functionality of string concatenation by += operator
* and implicit conversion from string to it's type.
*/
var assignableSb = new AssignableStringBuilder();
assignableSb = "Hello";
assignableSb += " World";
WriteLine(assignableSb);
/*
* Decorator pattern is used to add or extend functionality of an
* existing type. In this example we decorate the basic User class
* to have a last name when it becomes a VipUser.
*/
var user = new User("John", 24);
var vipUser = new VipUser(user, "Doe");
WriteLine(user);
WriteLine(vipUser);
/*
* Demonstration of C# extension methods to apply decorator pattern.
*/
var user2 = new User("Jane", 17);
var ageInfo = user2.IsAdult() ? "an adult" : "not an adult";
WriteLine($"{user2} is {ageInfo}");
var vipUser2 = user2.ConvertToVip("Doe");
WriteLine($"{vipUser2} is a VIP user now.");
/*
* Course exercise
*/
var dragon = new Dragon()
{
Age = 0
};
WriteLine(dragon.Fly());
WriteLine(dragon.Crawl());
}