缺少1个必需的位置参数 – ‘Self’?

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英文:

Missing 1 required positional argument - 'Self'?

问题

我有一个特定类的以下方法

    def make_payment(self, cost):

和主文件中的以下内容

    print(money_machine.make_payment(drink.cost))

为什么会返回这个错误?(我正在参加一个代码教程他的代码似乎没问题
TypeError: MoneyMachine.make_payment()缺少1个必需的位置参数'cost' 

主文件

>     from menu import Menu, MenuItem
>     from coffee_maker import CoffeeMaker
>     from money_machine import MoneyMachine
>     
>     """1print report
>     2check resources sufficies
>     process coins 
>     check transaction successful
>     make coffee
>     """
>     coffee_maker = CoffeeMaker()
>     menu = Menu()
>     money_machine = MoneyMachine
>     
>     is_on = True
>     while is_on:
>     
>         print(menu.get_items())
>         order = input("你的订单")
>         if order == '关闭':
>             is_on = False
>         elif order == "报告":
>             coffee_maker.report()
>         else:
>             drink = menu.find_drink(order)
>             if coffee_maker.is_resource_sufficient(drink):
>                 if money_machine.make_payment(drink.cost):
>                     coffee_maker.make_coffee(drink)

货币机器

    class MoneyMachine:
    
        货币单位 = "$"
    
        硬币面值 = {
            "quarters": 0.25,
            "dimes": 0.10,
            "nickles": 0.05,
            "pennies": 0.01
        }
    
        def __init__(self):
            self.profit = 0
            self.money_received = 0
    
        def 报告(self):
            """打印当前利润"""
            print(f"货币: {self.货币单位}{self.profit}")
    
        def 处理硬币(self):
            """返回插入的硬币计算得到的总额。"""
            print("请插入硬币。")
            for coin in self.硬币面值:
                self.money_received += int(input(f"有多少{coin}?: ")) * self.硬币面值[coin]
            return self.money_received
    
        def make_payment(self, cost):
            """当付款被接受时返回True,如果不够则返回False。"""
            print(self.money_received)
            self.处理硬币()
            if self.money_received >= cost:
                找零 = round(self.money_received - cost, 2)
                print(f"这是{self.货币单位}{找零}的找零。")
                self.profit += cost
                self.money_received = 0
                return True
            else:
                print("抱歉,钱不够。钱已退还。")
                self.money_received = 0
                return False
英文:

I have the following method of a certain class:

def make_payment(self, cost):

and the following at the main file:

print(money_machine.make_payment(drink.cost))

why is it returning this? (I am following a code-along session and everything seems to be fine with his code)
TypeError: MoneyMachine.make_payment() missing 1 required positional argument: 'cost'

MAIN:

> from menu import Menu, MenuItem
> from coffee_maker import CoffeeMaker
> from money_machine import MoneyMachine
>
> """1print report
> 2check resources sufficies
> process coins
> check transaction successful
> make coffee
> """
> coffee_maker = CoffeeMaker()
> menu = Menu()
> money_machine = MoneyMachine
>
> is_on = True
> while is_on:
>
> print(menu.get_items())
> order = input("your order: ")
> if order == 'off':
> is_on = False
> elif order == "report":
> coffee_maker.report()
> else:
> drink = menu.find_drink(order)
> if coffee_maker.is_resource_sufficient(drink):
> if money_machine.make_payment(drink.cost):
> coffee_maker.make_coffee(drink)

MONEY MACHINE:

class MoneyMachine:
CURRENCY = "$"
COIN_VALUES = {
"quarters": 0.25,
"dimes": 0.10,
"nickles": 0.05,
"pennies": 0.01
}
def __init__(self):
self.profit = 0
self.money_received = 0
def report(self):
"""Prints the current profit"""
print(f"Money: {self.CURRENCY}{self.profit}")
def process_coins(self):
"""Returns the total calculated from coins inserted."""
print("Please insert coins.")
for coin in self.COIN_VALUES:
self.money_received += int(input(f"How many {coin}?: ")) * self.COIN_VALUES[coin]
return self.money_received
def make_payment(self, cost):
"""Returns True when payment is accepted, or False if insufficient."""
print(self.money_received)
self.process_coins()
if self.money_received >= cost:
change = round(self.money_received - cost, 2)
print(f"Here is {self.CURRENCY}{change} in change.")
self.profit += cost
self.money_received = 0
return True
else:
print("Sorry that's not enough money. Money refunded.")
self.money_received = 0
return False

答案1

得分: 1

根据您的评论,问题在于您没有正确实例化您的类。

总的来说,您的实例化代码应该更像这样,这是正确实例化类的方法:

money_machine = MoneyMachine()

然后调用方法会正确实例化它,并将self传递进去,因此money_machine.make_payment(drink.cost)会按预期工作。

实例化类实际上是调用类的__init__()方法,这也是您在创建类的副本时需要定义任何必需参数的地方。例如:

class MoneyMachine():
    def __init__(self, currency_type):
        # 在这里必须用currency_type定义实例
        self.currency_type = currency_type
        self.profit = 0
        self.money_received = 0

usa_money_machine = MoneyMachine(currency_type='USD')

英文:

Per your comments, the issue is that you are not instantiating your class correctly.

Overall your instantiation code should be more like this, which is the correct way to instantiate a class:

money_machine = MoneyMachine()

then calling methods would insatiate it correctly and you pass self in, so money_machine.make_payment(drink.cost) would then work as expected.

Instantiating a class is essentially calling the class's __init__() method, this is also where you would define any required arguments if needed when creating a copy of the class. For example:

class MoneyMachine():
def __init__(self, currency_type):
# here you must instantiate with currency_type defined
self.currency_type = currency_type
self.profit = 0
self.money_received = 0

usa_money_machine = MoneyMachine(currency_type='USD')

huangapple
  • 本文由 发表于 2023年2月6日 21:54:57
  • 转载请务必保留本文链接:https://go.coder-hub.com/75362227.html
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