chapter 9

Author: rebuild-123

README.md

@@ -1,14 +1,15 @@
 # Python Head First Design Patterns 
 ## Chapters 
-[chapter 1(strategy)](https://github.com/rebuild-123/Python-Head-First-Design-Patterns/tree/main/strategy)-done 
-[chapter 2(observer)](https://github.com/rebuild-123/Python-Head-First-Design-Patterns/tree/main/observer)-done (Only swing has no translation.) 
-[chapter 3(decorator)](https://github.com/rebuild-123/Python-Head-First-Design-Patterns/tree/main/decorator)-done (Only io has no translation.) 
-[chapter 4(factory)](https://github.com/rebuild-123/Python-Head-First-Design-Patterns/tree/main/factory)-done 
-[chapter 5(singleton)](https://github.com/rebuild-123/Python-Head-First-Design-Patterns/tree/main/singleton)-done 
-[chapter 6(command)](https://github.com/rebuild-123/Python-Head-First-Design-Patterns/tree/main/command)-done (Only swing has no translation.) 
-[chapter 7(adapter)](https://github.com/rebuild-123/Python-Head-First-Design-Patterns/tree/main/adapter)-done 
-[chapter 7(facade)](https://github.com/rebuild-123/Python-Head-First-Design-Patterns/tree/main/facade/hometheater)-done 
-[chapter 8(templatemethod)](https://github.com/rebuild-123/Python-Head-First-Design-Patterns/tree/main/templatemethod)-done (applet and frame have no translation.) 
+[chapter 1(strategy)](https://github.com/rebuild-123/Python-Head-First-Design-Patterns/tree/main/strategy) 
+[chapter 2(observer)](https://github.com/rebuild-123/Python-Head-First-Design-Patterns/tree/main/observer) (Only swing has no translation.) 
+[chapter 3(decorator)](https://github.com/rebuild-123/Python-Head-First-Design-Patterns/tree/main/decorator) (Only io has no translation.) 
+[chapter 4(factory)](https://github.com/rebuild-123/Python-Head-First-Design-Patterns/tree/main/factory) 
+[chapter 5(singleton)](https://github.com/rebuild-123/Python-Head-First-Design-Patterns/tree/main/singleton) 
+[chapter 6(command)](https://github.com/rebuild-123/Python-Head-First-Design-Patterns/tree/main/command) (Only swing has no translation.) 
+[chapter 7(adapter)](https://github.com/rebuild-123/Python-Head-First-Design-Patterns/tree/main/adapter) 
+[chapter 7(facade)](https://github.com/rebuild-123/Python-Head-First-Design-Patterns/tree/main/facade/hometheater) 
+[chapter 8(templatemethod)](https://github.com/rebuild-123/Python-Head-First-Design-Patterns/tree/main/templatemethod) (applet and frame have no translation.) 
+chapter 9(iterator) - in translation 
 ## Introduction 
 1. Translated from [Head-First-Design-Patterns](https://github.com/bethrobson/Head-First-Design-Patterns) (java) 
 2. What are the differences between other Python version Head-First-Design-Patterns and ours? 

iterator/transition/DinerMenu.py

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+from typing import Final, Iterator, List
+
+from DinerMenuIterator import DinerMenuIterator
+from Menu import Menu
+from MenuItem import MenuItem
+
+
+class DinerMenu(Menu):
+ MAX_ITEMS: Final[int] = 6
+ numberOfItems: int = 0
+ menuItems: List[MenuItem]
+ 
+ def __init__(self):
+ self.menuItems = []
+ 
+ self.addItem("Vegetarian BLT","(Fakin') Bacon with lettuce & tomato on whole wheat", True, 2.99)
+ self.addItem("BLT","Bacon with lettuce & tomato on whole wheat", False, 2.99)
+ self.addItem("Soup of the day","Soup of the day, with a side of potato salad", False, 3.29)
+ self.addItem("Hotdog","A hot dog, with sauerkraut, relish, onions, topped with cheese",False, 3.05)
+ self.addItem("Steamed Veggies and Brown Rice","Steamed vegetables over brown rice", True, 3.99)
+ self.addItem("Pasta","Spaghetti with Marinara Sauce, and a slice of sourdough bread",True, 3.89)
+ 
+ def addItem(self, name: str, description: str, vegetarian: bool, price: float) -> None:
+ menuItem: MenuItem = MenuItem(name, description, vegetarian, price)
+ if self.numberOfItems >= self.MAX_ITEMS:
+ print("Sorry, menu is full! Can't add item to menu")
+ else:
+ self.menuItems.append(menuItem)
+ self.numberOfItems += 1
+ 
+ def getMenuItems(self) -> List[MenuItem]:
+ return self.menuItems
+ 
+ def createIterator(self) -> Iterator[MenuItem]:
+ return DinerMenuIterator(self.menuItems)
+ # return AlternatingDinerMenuIterator(menuItems)
+ 
+ # other menu methods here

iterator/transition/DinerMenuIterator.py

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+from typing import Iterator, List
+
+from typing import Optional
+
+from MenuItem import MenuItem
+
+
+class IllegalStateException(Exception): pass
+
+class DinerMenuIterator(Iterator[MenuItem]):
+ list: List[MenuItem]
+ position: int = 0
+ 
+ def __init__(self, list: List[MenuItem]):
+ self.list = list
+ 
+ def __next__(self) -> Optional[MenuItem]:
+ if self.hasNext():
+ menuItem: MenuItem = self.list[self.position]
+ self.position += 1
+ return menuItem
+ else:
+ raise StopIteration
+ 
+ def hasNext(self) -> bool:
+ if self.position >= len(self.list) or self.list[self.position] == None:
+ return False
+ else:
+ return True
+ 
+ def remove(self) -> None:
+ if self.position <= 0:
+ raise IllegalStateException("You can't remove an item until you've done at least one next()")
+ if self.list[self.position-1] != None:
+ for i in range(self.position-1, len(self.list)-1):
+ self.list[i] = self.list[i+1]
+ self.list[len(self.list)-1] = None

iterator/transition/Menu.py

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+from typing import Any, Iterator
+
+
+class Menu:
+ def createIterator(self) -> Iterator[Any]:
+ pass

iterator/transition/MenuItem.py

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+class MenuItem:
+ name: str
+ description: str
+ vegetarian: bool
+ price: float
+ 
+ def __init__(self, name: str, description: str, vegetarian: bool, price: float):
+ self.name = name
+ self.description = description
+ self.vegetarian = vegetarian
+ self.price = price
+ 
+ def getName(self) -> str:
+ return self.name
+ 
+ def getDescription(self) -> str:
+ return self.description
+ 
+ def getPrice(self) -> float:
+ return self.price
+ 
+ def isVegetarian(self) -> bool:
+ return self.vegetarian

iterator/transition/PancakeHouseMenu.py

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+from typing import Iterator, List
+
+from Menu import Menu
+from MenuItem import MenuItem
+
+
+class PancakeHouseMenu(Menu):
+ menuItems: List[MenuItem]
+ 
+ def __init__(self):
+ self.menuItems = []
+ 
+ self.addItem("K&B's Pancake Breakfast", "Pancakes with scrambled eggs and toast", True,2.99)
+ self.addItem("Regular Pancake Breakfast", "Pancakes with fried eggs, sausage", False,2.99)
+ self.addItem("Blueberry Pancakes","Pancakes made with fresh blueberries and blueberry syrup",True,3.49)
+ self.addItem("Waffles","Waffles with your choice of blueberries or strawberries",True,3.59)
+ 
+ def addItem(self, name: str, description: str, vegetarian: bool, price: float) -> None:
+ menuItem: MenuItem = MenuItem(name, description, vegetarian, price)
+ self.menuItems.append(menuItem)
+ 
+ def getMenuItems(self) -> List[MenuItem]:
+ return self.menuItems
+ 
+ def createIterator(self) -> Iterator[MenuItem]:
+ return iter(self.menuItems)
+ 
+ # other menu methods here

iterator/transition/Waitress.py

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+from typing import Any, Iterator, List
+
+from Menu import Menu
+from MenuItem import MenuItem
+
+
+class Waitress:
+ menus: List[Menu]
+ 
+ def __init__(self, menus: List[Menu]):
+ self.menus = menus
+ 
+ def printMenu(self) -> None:
+ menuIterator: Iterator[Any] = iter(self.menus)
+ menu = next(menuIterator, None) # not all "menu" has the method "hasNext".
+ while menu != None:
+ self.printMenu_(menu.createIterator())
+ menu = next(menuIterator, None)
+ 
+ # authors' java code has two "printMenu", which cannot be translated to python.
+ def printMenu_(self, iterator: Iterator[Any]) -> None:
+ menuItem = next(iterator, None) # not all "iterator" has the method "hasNext".
+ while menuItem != None:
+ print(f"{menuItem.getName()}, ", end="")
+ print(f"{menuItem.getPrice()} -- ", end="")
+ print(menuItem.getDescription())
+ menuItem = next(iterator, None)