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Command Pattern

# Command Pattern is good for batch processes with behavioral class

class Document:
    text = ""
    def __str__(self):
        return self.text

import abc
class DocumentCommand(abc.ABC):
    doc = None
    @abc.abstractmethod
    def execute(self):
        pass
    @abc.abstractmethod
    def undo(self):
        pass

class AddStrCommand(DocumentCommand):
    def __init__(self, doc, txt):
        self.text = txt
        self.doc = doc
    def execute(self):
        self.doc.text += self.text
        return self.doc
    def undo(self):
        return DeleteStrCommand(self.doc, self.text).execute()


class DeleteStrCommand(DocumentCommand):
    def __init__(self, doc, txt):
        self.text = txt
        self.doc = doc
    def execute(self):
        idx = self.doc.text.find(self.text)
        if idx == -1:
            return self.doc
        self.doc.text = self.doc.text[:idx]
        return self.doc
    def undo(self):
        return AddStrCommand(self.doc, self.text).execute()

doc = Document()
editingTexts = [AddStrCommand(doc,"hello\n"), AddStrCommand(doc,"My name is Chang\n"),  AddStrCommand(doc,"I hope you have a good day")]
for c in editingTexts:
    c.execute()

print(doc)
print(editingTexts[-1].undo())
print(editingTexts[-1].undo())
d = DeleteStrCommand(doc,"My name is Chang\n")
print(d.execute())
print(d.undo())
print(doc)

Extra resources:

https://www.tutorialspoint.com/design_pattern/command_pattern.htm

import abc
class Order(abc.ABC):
    @abc.abstractmethod
    def execute(self):
        pass

class Stock:
    def __init__(self, name):
        self.name = name

    def buy(self):
        print(f"Stock {self.name} bought", end=" ")

    def sell(self):
        print(f"Stock {self.name} sold", end=" ")

class BuyStock(Order):
    def __init__(self, stock, quantity):
        self.stock = stock
        self.quantity = quantity

    def execute(self):
        self.stock.buy()
        print(f"{self.quantity}")

class SellStock(Order):
    def __init__(self, stock, quantity):
        self.stock = stock
        self.quantity = quantity

    def execute(self):
        self.stock.sell()
        print(f"{self.quantity}")

class Broker:
    def __init__(self, name):
        self.name = name
        self.orderList = []

    def addOrder(self, order):
        self.orderList.append(order)

    def placeOrders(self):
        for o in self.orderList:
            o.execute()

broker = Broker("Fidelity")
amazonStock = Stock("Amazon")
buy1 = BuyStock(amazonStock, 10)
sell1 =SellStock(amazonStock, 5)
broker.addOrder(buy1)
broker.addOrder(sell1)

pltrStock = Stock("PLTR")
buy2 = BuyStock(pltrStock, 100)
sell2 =SellStock(pltrStock, 9)

broker.addOrder(buy2)
broker.addOrder(sell2)
broker.placeOrders()
class Pet:
    def __init__(self, kind, name):
        self.kind = kind
        self.name = name

class FeedPet:
    def __init__(self, pet, food):
        self.pet = pet
        self.food = food

    def execute(self):
        print(f"{self.pet.kind},  {self.pet.name} eats {self.food}")

class WalkPet:
    def __init__(self, pet, place):
        self.pet = pet
        self.place = place

    def execute(self):
        print(f"{self.pet.name} eats {self.place}")

class PlayPet:
    def __init__(self, pet, min):
        self.pet = pet
        self.min = min

    def execute(self):
        print(f"{self.pet.name} plays for {self.min}")

class AnimalFarm:
    def __init__(self, name):
        self.name = name
        self.todoList = []

    def addTodo(self, deed):
        self.todoList.append(deed)

    def doTodoList(self):
        for do in self.todoList:
            do.execute()

farm = AnimalFarm("Seattle Animal Farm")
horse = Pet("Horse", "Thunder")
cow = Pet("Cow", "Moo")
cat = Pet("cat", "Muze")
dog = Pet("dog", "Win")

farm.addTodo(FeedPet(horse, "carrot"))
farm.addTodo(PlayPet(horse, "30"))
farm.addTodo(WalkPet(dog, "dog park"))
farm.addTodo(FeedPet(cat, "salmon"))
farm.addTodo(FeedPet(cow, "hay"))

farm.doTodoList()

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