How to change default discount in python using classes and inheriance?

December 4, 2022

I was trying to change the discount rate of a particular sub class, while the default is set at 0, and in subclass it changes to 5, however, this is not refelected.

I cannot switch the discount scheme on Class B, because all class need to have access on it.

class A:
    def __init__(self, x, y, discount=0):
        self.discount=0
        if self.discount>0:
            discount = self.discount
        else:
            discount=0
        self.discount=discount
        self.x=x
        self.y=y
        self.discount=discount
        discount=5
class B(A):
    def __init__ (self,x,y,z):
        super().__init__(x,y)
        B.z=z
        B.discount=5
        
class C(A):
    def __init__ (self,x,y,a):
        super().__init__(x,y) 
        C.a=a
        C.discount = 10
        a = y*10

one=A(1,2)
print(one.x)
print(one.discount)
two = B(1,2,3)
print(two.x)
print(two.z)
print(two.discount)
three = C(4,5,6)
print(three.x)
print(three.discount)

Output:

Tried to do some calculations and integrate methods, but it only works for methoid but not on the class, as you can see, the discount is set to 0 and doesn’t change.

>Solution :

The constructor of your A class seems quite confusing. If the only thing you need is to check if the discount parameter is greater than 0 and set it to your instance’s discount variable, you can simplify your code like this:

class A:
    def __init__(self, x, y, discount=0):
        self.discount=0
        if discount>0:
            self.discount = discount
        self.x=x
        self.y=y

Moreover, when you try to modify an instance variable in a subclass, you can still use self:

class B(A):
    def __init__ (self,x,y,z):
        super().__init__(x,y)
        self.z=z
        self.discount=5
        
class C(A):
    def __init__ (self,x,y,a):
        super().__init__(x,y) 
        self.a=a
        self.discount = 10
        a = y*10

Running the commands again, you ‘ll get: