多类继承Python的错误

Question

import matplotlib.pyplot as plt
import numpy as np
import plotly.graph_objects as go # run "pip install plotly==4.9.0" in your terminal to install plotly
import yfinance as yf
import numpy as np
import ast

eurusd = yf.Ticker("EURUSD=X")
usd_to_eur = 1 / (eurusd.info["ask"])
eur_to_usd = 1 * eurusd.info["ask"]

class Asset:
    def __init__(self,name, ticker, amount):
        self.amount = amount
        self.name = name
        self.ticker = ticker
        self.price = yf.Ticker(self.ticker).info["regularMarketPrice"]

class Usd_asset(Asset):
    def __init__(self, name, ticker, amount, buy_price):
        super().__init__(name, ticker, amount)
        self.buy_price = buy_price
        self.buy_price_eur = [x * usd_to_eur for x in self.buy_price]
        self.price_usd = yf.Ticker(self.ticker).info["regularMarketPrice"]
        self.price_eur = self.price_usd * usd_to_eur

class Crypto(Asset):
    def __init__(self, name, ticker, amount):
        super().__init__(name, ticker, amount)
        print("crypto")


class Crypto_Usd(Crypto, Usd_asset):
    def __init__(self, name, ticker, amount, buy_price):
        Usd_asset.__init__(self, name = name, ticker = ticker, amount = amount, buy_price = buy_price)
        Crypto.__init__(self, name = name, ticker = ticker, amount = amount)
        print("crypto usd")

每当我运行它时，我都会得到以下信息：

Attribute Error: Type object 'Usd_asset' has no attribute '_Crypto_Usd__init'

我在这里做错了什么？

我的目标是拥有一个继承自 Crypto 和 Usd_asset 的类。 它们又都继承自 Asset。

Answer 1

因为您的实例是 Crypto_Usd，当您使用 super() 时，您没有按预期获得类 Asset => 替换调用 super().__init(...)by @987654323 @

Answer 2

在 Python 3.8.6 中，我无法重现该错误，但出现了其他奇怪的行为：

class Asset:
  def __init__(self, name):
    print("init Asset")
    self.name = name
class Usd_asset(Asset):
  def __init__(self, name):
    print("init Usd_asset")
    super().__init__(name)
    print("done Usd_asset")
class Crypto(Asset):
  def __init__(self, name):
    print("init Crypto", Crypto.__mro__)
    super().__init__(name)
    print("done Crypto")
class Crypto_Usd(Crypto, Usd_asset):
  def __init__(self, name):
    print("init Crypto_Usd")
    Usd_asset.__init__(self, name = name)
    Crypto.__init__(self, name = name)
    print("done Crypto_Usd")

print("\nCrypto('bar')")
x = Crypto('bar')
print("\nCrypto_Usd('foo')")
a = Crypto_Usd('foo')

输出：

Crypto('bar')
init Crypto (<class '__main__.Crypto'>, <class '__main__.Asset'>, <class 'object'>)
init Asset
done Crypto

Crypto_Usd('foo')
init Crypto_Usd
init Usd_asset
init Asset
done Usd_asset
init Crypto (<class '__main__.Crypto'>, <class '__main__.Asset'>, <class 'object'>)
init Usd_asset        ## <<<--- strange
init Asset
done Usd_asset
done Crypto
done Crypto_Usd

问题是在Crypto.__init__() 方法中调用Usd_asset.__init__()。 __mro__ 表明 Asset 是唯一的超类。

使用完整代码，我在Crypto.__init__() 中得到一个异常

__init__() missing 1 required positional argument: 'buy_price'

它尝试调用Usd_asset.__init__()

解决方案

不要在用于多重继承的类中使用super()。或者可能永远不要使用super()，因为您不知道该类是否会用于多重继承。

总是写Class.method(self, arguments)

class Usd_asset(Asset):
    def __init__(self, name, ticker, amount, buy_price):
        Asset.__init__(self, name, ticker, amount)
        self.buy_price = buy_price
        self.buy_price_eur = [x * usd_to_eur for x in self.buy_price]
        self.price_usd = yf.Ticker(self.ticker).info["regularMarketPrice"]
        self.price_eur = self.price_usd * usd_to_eur

class Crypto(Asset):
    def __init__(self, name, ticker, amount):
        Asset.__init__(self, name, ticker, amount)
        print("crypto")

---

编辑

Crypto.__init__()中的super()之所以选择Usd_asset.__init__()是因为super()或super(Crypto, self)使用self.__class__.__mro__找到Crypto类的第一个父类。

如果self 是Crypto 的实例

self.__class__.__mro__ (<class '__main__.Crypto'>, <class '__main__.Asset'>, <class 'object'>)

Asset 将被选中。

如果self 是Crypto_Usd 的实例

self.__class__.__mro__ (<class '__main__.Crypto_Usd'>, <class '__main__.Crypto'>, <class '__main__.Usd_asset'>, <class '__main__.Asset'>, <class 'object'>)

Usd_asset 将被选中。

class Crypto(Asset):
  def __init__(self, name):
    print("init Crypto", Crypto.__mro__)
    print("self.__class__.__mro__", self.__class__.__mro__)
    super().__init__(name)
    print("done Crypto")

__mro__ 元组不显示多重继承，因此会产生这种奇怪的行为。

Answer 3

import matplotlib.pyplot as plt
import numpy as np
import plotly.graph_objects as go # run "pip install plotly==4.9.0" in your terminal to install plotly
import yfinance as yf
import numpy as np
import ast

eurusd = yf.Ticker("EURUSD=X")
usd_to_eur = 1 / (eurusd.info["ask"])
eur_to_usd = 1 * eurusd.info["ask"]

class Asset:
    def __init__(self,name, ticker, amount):
        self.amount = amount
        self.name = name
        self.ticker = ticker
        self.price = yf.Ticker(self.ticker).info["regularMarketPrice"]

class Usd_asset(Asset):
    def __init__(self, name, ticker, amount, buy_price):
        super().__init__(name, ticker, amount)
        self.buy_price = buy_price
        self.buy_price_eur = [x * usd_to_eur for x in self.buy_price]
        self.price_usd = yf.Ticker(self.ticker).info["regularMarketPrice"]
        self.price_eur = self.price_usd * usd_to_eur

class Crypto(Asset):
    def __init__(self, name, ticker, amount):
        super().__init__(name, ticker, amount)
        print("crypto")


class Crypto_Usd(Crypto, Usd_asset):
    def __init__(self, name, ticker, amount, buy_price):
        Usd_asset.__init__(self, name = name, ticker = ticker, amount = amount, buy_price = buy_price)
        Crypto.__init__(self, name = name, ticker = ticker, amount = amount)
        print("crypto usd")