[Solved] What will be the output of this code?class A: def who(self): return 'A' class B(A): def who(self): return 'B' class C(A): def who(self): return 'C' class D(B, C): pass print(D().who()) | Python

Python - Multiple Inheritance and Method Resolution

What will be the output of this code?

class A:
    def who(self):
        return 'A'
class B(A):
    def who(self):
        return 'B'
class C(A):
    def who(self):
        return 'C'
class D(B, C):
    pass
print(D().who())

AA

BB

CC

DError

Step-by-Step Solution

Solution:

Step 1: Understand class hierarchy
D inherits from B and C; B and C inherit from A. D does not override who().
Step 2: Apply MRO to find who()
MRO for D is D, B, C, A. So who() from B is called first.
Final Answer:
B -> Option B
Quick Check:
MRO lookup finds B's who() first [OK]

Quick Trick: MRO checks left to right in base classes list [OK]

Common Mistakes:

Choosing C's method instead of B's
Expecting error due to multiple inheritance

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What will be the output of this code?

Step 1: Understand class hierarchy

Step 2: Apply MRO to find who()

Final Answer:

Quick Check:

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