pjensen/flyweightdemo

The Flyweight GOF pattern in C++

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FlyWeight Demo]

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• [QUEEN of HEARTS] @ 0x9810020
• [JACK of SPADES] @ 0x9810048
• [5 of HEARTS] @ 0x9810070
• [2 of CLUBS] @ 0x9810098
• [QUEEN of DIAMONDS] @ 0x98100c0
• [ACE of SPADES] @ 0x98100e8
• [KING of HEARTS] @ 0x9810110
• [QUEEN of DIAMONDS] @ 0x98100c0
• [2 of CLUBS] @ 0x9810098
• [5 of HEARTS] @ 0x9810070
• [JACK of SPADES] @ 0x9810048
• [JACK of HEARTS] @ 0x9810138

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##FlyweightDemo

This is the driver (client) program for both Card, and CardCache. We actually only refer to CardCache and it handles and enforces the Flyweight property for us.

CardCache

CardCache is a singleton class that maintains a pool of cards. The pool is a map that maps (suite, value) pairs to a card. It also implements the factory pattern, where getCard returns the only instance of the requested card.

Card

This is the Card class. Please note that it only supports the fundementals of a Card and NOT a deck of Cards. getValue(), setValue(), getSuite(), setSuite(), getSuiteString(), getValueString().

Also the == operator and << are both supported. It does not make sense to support < or > since in different games the rules change. I thought about making them virtual that way they could be over-riden, but I am not sure it would have been applicable to this demonstration.

NOTE: The data type(s) suite, and value also exist.

typedef enum suite {HEARTS, CLUBS, DIAMONDS, SPADES};
typedef enum value {TWO,THREE,FOUR,FIVE,SIX,SEVEN,EIGHT,NINE,TEN,
				JACK,QUEEN,KING,ACE};

Suppose you wanted to create the QUEEN of DIAMONDS.

Card myCard = Card(DIAMONDS, QUEEN);

NOTE: The default constructor does nothing; the destructor does nothing. however, I've suppied two explicit constructors.

// Let s be a suite, Let v be a value.
Card(s, v) == Card(v, s) would be a valid statement.

I did this because I realized that I didn't like it the way I had it. Card(DIAMONDS, QUEEN), I don't think of THE QUEEN OF DIAMONDS like exactly that way. So it makes sense to at least provide an option for the consruction of the object in whichever order.