如何創建多個繼承類的實體？-有解無憂

我有這個代碼：

class Person:
    def __init__(self, name, last_name, age):
        self.name = name
        self.last_name = last_name
        self.age = age 

class Student(Person):
    def __init__(self, name, last_name, age, indexNr, notes):
        super().__init__(name, last_name, age)
        self.indexNr = indexNr
        self.notes = notes

class Employee(Person):
    def __init__(self, name, last_name, age, salary, position):
        super().__init__(name, last_name, age)
        self.salary = salary
        self.position = position

class WorkingStudent(Student, Employee):
    def __init__(self, name, last_name, age, indexNr, notes, salary, position):
        Student.__init__(name, last_name, age, indexNr, notes)
        Employee.__init__(name, last_name, age, salary, position)

我想像這樣創建一個 WorkingStudent 實體：

ws = WorkingStudent("john", "brown", 18, 1, [1,2,3], 1000, 'Programmer')

但它不起作用，我收到此錯誤：

TypeError: __init__() missing 1 required positional argument: 'notes'

或者我在這里做錯了什么？另外，我已經super()在 WorkingStudent 類中嘗試過，但它只呼叫第一個傳遞類的建構式。即在這種情況下Student

注意：我已經經歷了多個 StackOverflow 查詢，但我找不到任何可以回答這個問題的東西。（或者也許我錯過了）。

uj5u.com熱心網友回復：

代替顯式類，用于super()沿 mro 傳遞引數：

class Person:
    def __init__(self, name, last_name, age):
        self.name = name
        self.last_name = last_name
        self.age = age 

class Student(Person):
    def __init__(self, name, last_name, age, indexNr, notes, salary, position):
        # since Employee comes after Student in the mro, pass its arguments using super
        super().__init__(name, last_name, age, salary, position)
        self.indexNr = indexNr
        self.notes = notes

class Employee(Person):
    def __init__(self, name, last_name, age, salary, position):
        super().__init__(name, last_name, age)
        self.salary = salary
        self.position = position

class WorkingStudent(Student, Employee):
    def __init__(self, name, last_name, age, indexNr, notes, salary, position):
        # pass all arguments along the mro
        super().__init__(name, last_name, age, indexNr, notes, salary, position)

# uses positional arguments            
ws = WorkingStudent("john", "brown", 18, 1, [1,2,3], 1000, 'Programmer')
# then you can print stuff like
print(f"My name is {ws.name} {ws.last_name}. I'm a {ws.position} and I'm {ws.age} years old.")
# My name is john brown. I'm a Programmer and I'm 18 years old.

檢查先生：

WorkingStudent.__mro__
(__main__.WorkingStudent,
 __main__.Student,
 __main__.Employee,
 __main__.Person,
 object)

當你創建一個 WorkingStudent 的實體時，最好傳遞關鍵字引數，這樣你就不必擔心弄亂引數的順序。

由于 WorkingStudent 將屬性的定義推遲到父類，因此立即將所有引數傳遞給層次結構，super().__init__(**kwargs)因為子類不需要知道它不處理的引數。第一個父類是 Student，所以 self.IndexNr 等在那里定義。mro 中的下一個父類是 Employee，因此從 Student 中，將剩余的關鍵字引數傳遞給它，super().__init__(**kwargs)再次使用。從 Employee 開始，定義在那里定義的屬性，然后super().__init__(**kwargs)再次通過 mro（到 Person）傳遞其余的屬性。

class Person:
    def __init__(self, name, last_name, age):
        self.name = name
        self.last_name = last_name
        self.age = age 

class Student(Person):
    def __init__(self, indexNr, notes, **kwargs):
        # since Employee comes after Student in the mro, pass its arguments using super
        super().__init__(**kwargs)
        self.indexNr = indexNr
        self.notes = notes

class Employee(Person):
    def __init__(self, salary, position, **kwargs):
        super().__init__(**kwargs)
        self.salary = salary
        self.position = position

class WorkingStudent(Student, Employee):
    def __init__(self, **kwargs):
        # pass all arguments along the mro
        super().__init__(**kwargs)

# keyword arguments (not positional arguments like the case above)
ws = WorkingStudent(name="john", last_name="brown", age=18, indexNr=1, notes=[1,2,3], salary=1000, position='Programmer')

uj5u.com熱心網友回復：

問題：對于最派生的類，我們有很多引數，需要用于初始化所有基類。但是，在 Python 的多繼承系統 withsuper()中，接下來要初始化的類取決于可能已經在另一個類中確定的 MRO（方法決議順序）。因此，當我們使用多重繼承時，我們不知道在使用時會__init__呼叫哪個類super()。

解決方案：為引數使用一致的名稱，然后利用**kwargs，以便每個類接受它關心的（顯式命名的）引數，并轉發其余的。

看起來像：

class Person:
    def __init__(self, name, last_name, age):
        self.name = name
        self.last_name = last_name
        self.age = age 

class Student(Person):
    def __init__(self, indexNr, notes, **kwargs):
        super().__init__(**kwargs)
        self.indexNr = indexNr
        self.notes = notes

class Employee(Person):
    def __init__(self, salary, position, **kwargs):
        super().__init__(**kwargs)
        self.salary = salary
        self.position = position

class WorkingStudent(Student, Employee):
    def __init__(self, **kwargs):
        super().__init__(**kwargs)

強制客戶端代碼使用關鍵字引數對客戶端來說是更多的作業，但它也有助于防止錯誤位置引數的順序錯誤。

uj5u.com熱心網友回復：

這似乎可行，但并不美觀。我承認我對 Python 中的多重繼承并不熟悉，我認為這可能不是最正確的方式。希望其他人能給出更好的答案。

class Person:
    def __init__(self, name, last_name, age):
        self.name = name
        self.last_name = last_name
        self.age = age


class Student(Person):
    def __init__(self, name, last_name, age, indexNr, notes):
        Person.__init__(self, name, last_name, age)
        self.indexNr = indexNr
        self.notes = notes


class Employee(Person):
    def __init__(self, name, last_name, age, salary, position):
        Person.__init__(self, name, last_name, age)
        self.salary = salary
        self.position = position


class WorkingStudent(Student, Employee):
    def __init__(self, name, last_name, age, indexNr, notes, salary, position):
        Student.__init__(self, name, last_name, age, indexNr, notes)
        Employee.__init__(self, name, last_name, age, salary, position)


ws = WorkingStudent("john", "brown", 18, 1, [1, 2, 3], 1000, 'Programmer')
print(ws)

輸出：

<__main__.WorkingStudent object at 0x000002526F11F3D0>

uj5u.com熱心網友回復：

這是實作目標的最簡單方法。
如果您的 WorkingStudent 類像這樣繼承 Student 和 Employee 類，

class WorkingStudent(Student, Employee):
    def __init__(self, name, last_name, age, indexNr, notes, salary, position):
        Student.__init__(self, name, last_name, age, indexNr, notes)
        Employee.__init__(self, name, last_name, age, salary, position)


ws = WorkingStudent("john", "brown", 18, 1, [1, 2, 3], 1000, 'Programmer')
print(ws)
print(ws.name)
print(ws.age)

你的輸出將是......

輸出：

<位于 0x7fc6c4d8ba10 的主.WorkingStudent 物件>
john
18
[1, 2, 3]

轉載請註明出處，本文鏈接：https://www.uj5u.com/qita/478557.html

標籤：Python 哎呀多重继承

上一篇：如何限制某些屬性從外部更改但在Python中保存驗證

下一篇：洗掉bash或Python中所有出現的重復行，并僅獲取唯一行