Code Explanation:
🔹 1. Defining Class A
class A:
x = "A"
Creates a base class A
Defines a class variable x with value "A"
All subclasses inherit this unless they override it
🔹 2. Defining Class B (Overrides x)
class B(A):
x = "B"
B inherits from A
Defines its own class variable x
This overrides A.x inside class B
📌 Now:
B.x → "B"
🔹 3. Defining Class C (Overrides x)
class C(A):
x = "C"
C also inherits from A
Defines its own x
Overrides A.x inside C
📌 Now:
C.x → "C"
🔹 4. Defining Class D (Multiple Inheritance)
class D(B, C):
pass
D inherits from both B and C
Does not define x
Normally, Python would use MRO to decide between B.x and C.x
📌 MRO of D:
D → B → C → A → object
🔹 5. Creating an Instance of D
d = D()
Creates an object d
At this moment:
d has no instance attribute x
Accessing d.x would follow MRO and give "B"
🔹 6. Assigning an Instance Attribute
d.x = "X"
Creates an instance variable x inside d
Stored in d.__dict__
This shadows all class variables named x
📌 Instance attributes have higher priority than:
Class attributes
Inherited attributes
MRO rules
🔹 7. Accessing d.x
print(d.x)
Attribute lookup order:
Instance dictionary (d.__dict__) → ✅ finds "X"
Class D → not checked
Class B, C, A → not checked
✅ Final Output
X
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