public static void Test()
{
/*
* Scenario: we've had a concrete credit card class and we needed new methods
* for air travel and food supplies cashback calculation. Instead of adding to the interface,
* and then implementing them in each sub-class, we simply defined only 1 method
* in the CreditCard interface - accept() which takes on a visitor who supplies
* the functionality we need. Thus, we had to violate the OCP in the CreditCard interface
* and implementations **only** once, and have opened our hierarchy to future behavioral extensions.
*/
var bronze = new BronzeCreditCard();
var silver = new SilverCreditCard();
var gold = new GoldCreditCard();
// we only need to create 1 visitor, which can interact with our 3 objects
var airtraverlVisitor = new AirtravelOfferVisitor();
bronze.Accept(airtraverlVisitor);
silver.Accept(airtraverlVisitor);
gold.Accept(airtraverlVisitor);
var foodVisitor = new FoodOfferVisitor();
gold.Accept(foodVisitor);
}
public void VisitSilverCreditCard(SilverCreditCard card)
{
Console.WriteLine("The Silver credit card has 0.3% cashback for food supplies.");
}
public void VisitSilverCreditCard(SilverCreditCard card)
{
Console.WriteLine("The Silver credit card has 2.5% cashback on air-travel purchases.");
}