Python從父類繼承變量

Question

對不起，如果我不解釋那么好，但我會盡我所能：

所以我想從Parent類繼承變量，但我不想在創建Child類的實例時再次傳遞它們，因為我認為這是多余的。 我只是想使用來自Parent的眼睛顏色。 請參閱下面的示例代碼，了解我的意思

這是有效的：

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


class Child(Parent):
    def __init__(self, gender, 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)

這就是我想要的：

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


class Child(Parent):
    def __init__(self, gender):
        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

你問的是沒有意義的：

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


class Child(Parent):
    def __init__(self, gender):
        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)

在兒童中，參數eye_color和長度來自任何地方。

如果要重用父對象， rassar示例很好。

您還可以執行以下操作：

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

要么

class Parent:
    def __init__(self, eye_color="", length=0):
        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, y.length)

Answer 2

您可以嘗試將Parent實例傳遞給Child初始化程序...這可能是您最接近的。

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一個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)