Python的繼承父類變量

Question

很抱歉，如果我不解釋它是很好，但我會盡我所能：

所以我想繼承父類中的變量，但我不希望在創建Child類的實例時再次傳遞它們，因爲我認爲這是多餘的。例如，我只想使用Parent的眼睛顏色。請參見下面的示例代碼我的意思

這是什麼在起作用：

class Parent: 
    def __init__(self, eye_color, length): 
     self.eye_color = str(eye_color) 
     self.length = length 


class Child(Parent): 
    def __init__(self, gender, eye_color, length): 
     super().__init__(eye_color, length) 
     self.gender = str(gender) 

x = Parent("Blue", 2) 
y = Child("Men", "Blue", 2) 

print(x.eye_color, x.length) 
print(y.gender, x.length) 

這是我莫名其妙地想：

class Parent: 
    def __init__(self, eye_color, length): 
     self.eye_color = str(eye_color) 
     self.length = length 


class Child(Parent): 
    def __init__(self, gender): 
     super().__init__(eye_color, length) 
     self.gender = str(gender) 

x = Parent("Blue", 2) 
y = Child("Men") 

print(x.length, x.eye_color) 
print(y.gender, x.length) 

Answer 1

你可以嘗試通過一個Parent實例的Child初始化...這可能是最接近你會得到的。

class Parent: 
    def __init__(self, eye_color, length): 
     self.eye_color = str(eye_color) 
     self.length = length 


class Child(Parent): 
    def __init__(self, gender, parent): 
     super().__init__(parent.eye_color, parent.length) 
     self.gender = str(gender) 

x = Parent("Blue", 2) 
y = Child("Men", x) 

print(x.length, x.eye_color) 
print(y.gender, x.length) 

你可以做的另一件事是持有last_parent變量：

global last_parent 

class Parent: 
     def __init__(self, eye_color, length): 
      self.eye_color = str(eye_color) 
      self.length = length 
      last_parent = self 


class Child(Parent): 
    def __init__(self, gender): 
     super().__init__(last_parent.eye_color, last_parent.length) 
     self.gender = str(gender) 

x = Parent("Blue", 2) 
y = Child("Men") 

print(x.length, x.eye_color) 
print(y.gender, x.length) 

Answer 2

你問什麼沒有意義：

class Parent: 
    def __init__(self, eye_color, length): 
     self.eye_color = str(eye_color) 
     self.length = length 


class Child(Parent): 
    def __init__(self, gender): 
     super().__init__(eye_color, length) 
     self.gender = str(gender) 

x = Parent("Blue", 2) 
y = Child("Men") 

print(x.length, x.eye_color) 
print(y.gender, x.length) 

在孩子，參數eye_color和長度都來自無處。

rassar如果要重新使用父對象，示例很不錯。

你也可以做到以下幾點：

class Parent: 
    # def __init__(self, eye_color=(default value here), length=(default value here)): 
    def __init__(self, eye_color="", length=0): 
     self.eye_color = str(eye_color) 
     self.length = length 

OR

class Parent: 
    def __init__(self, eye_color, length): 
     self.eye_color = str(eye_color) 
     self.length = length 

class Child(Parent): 
    def __init__(self, gender, *args, **kwargs): 
     super().__init__(*args, **kwargs) 
     self.gender = str(gender) 

x = Parent("Blue", 2) 
y = Child("Men") # Work with first example of Parent 
y = Child("Men", eye_color="Blue", length=2) # Work with first 
y = Child("Men", "Blue", 2) # Work with second example 

print(x.length, x.eye_color) 
print(y.gender, x.length)