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Class for Each Combination

Метки: python

One solution is to create an individual class for every combination. Each class describes the drink and is responsible for the cost etc. The resulting menu is huge, and a part of the class diagram would look something like this:

The key to using this method is to find the particular combination you want. So, once you’ve found the drink you would like, here is how you would use it, as shown in the CoffeeShop class in the following code:

# Decorator/nodecorators/CoffeeShop.py
# Coffee example with no decorators

class Espresso: pass
class DoubleEspresso: pass
class EspressoConPanna: pass

class Cappuccino:
    def __init__(self):
        self.cost = 1
        self.description = "Cappucino"
    def getCost(self):
        return self.cost
    def getDescription(self):
        return self.description

class CappuccinoDecaf: pass
class CappuccinoDecafWhipped: pass
class CappuccinoDry: pass
class CappuccinoDryWhipped: pass
class CappuccinoExtraEspresso: pass
class CappuccinoExtraEspressoWhipped: pass
class CappuccinoWhipped: pass

class CafeMocha: pass
class CafeMochaDecaf: pass
class CafeMochaDecafWhipped:
    def __init__(self):
        self.cost = 1.25
        self.description = \
          "Cafe Mocha decaf whipped cream"
    def getCost(self):
        return self.cost
    def getDescription(self):
        return self.description

class CafeMochaExtraEspresso: pass
class CafeMochaExtraEspressoWhipped: pass
class CafeMochaWet: pass
class CafeMochaWetWhipped: pass
class CafeMochaWhipped: pass

class CafeLatte: pass
class CafeLatteDecaf: pass
class CafeLatteDecafWhipped: pass
class CafeLatteExtraEspresso: pass
class CafeLatteExtraEspressoWhipped: pass
class CafeLatteWet: pass
class CafeLatteWetWhipped: pass
class CafeLatteWhipped: pass

cappuccino = Cappuccino()
print((cappuccino.getDescription() + ": $" +
  `cappuccino.getCost()`))

cafeMocha = CafeMochaDecafWhipped()
print((cafeMocha.getDescription()
  + ": $" + `cafeMocha.getCost()`))

And here is the corresponding output:

Cappucino: $1.0
Cafe Mocha decaf whipped cream: $1.25

You can see that creating the particular combination you want is easy, since you are just creating an instance of a class. However, there are a number of problems with this approach. Firstly, the combinations are fixed statically so that any combination a customer may wish to order needs to be created up front. Secondly, the resulting menu is so huge that finding your particular combination is difficult and time consuming.