Python的继承父类变量

Question

很抱歉，如果我不解释它是很好，但我会尽我所能：

所以我想继承父类中的变量，但我不希望在创建Child类的实例时再次传递它们，因为我认为这是多余的。例如，我只想使用Parent的眼睛颜色。请参见下面的示例代码我的意思

这是什么在起作用：

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) 

这是我莫名其妙地想：

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

你可以尝试通过一个Parent实例的Child初始化...这可能是最接近你会得到的。

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变量：

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

你问什么没有意义：

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，参数eye_color和长度都来自无处。

rassar如果要重新使用父对象，示例很不错。

你也可以做到以下几点：

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)