Identify the bug in the following decorator implementation that causes incorrect behavior when stacking decorators:

medium🐞 Bug Identification Q14 of Q15

OOP & Design Patterns - Decorator Pattern - Wrapping Behaviour Without Subclassing

ALine 5: Recursive call to self.cost() instead of super().cost() causes infinite recursion

BLine 6: Incorrect string formatting in description

CLine 2: Incorrect call to super().__init__

DLine 4: Missing amount parameter default value

Step-by-Step Solution

Step 1: Analyze cost() method
cost() calls self.cost() recursively, causing infinite recursion instead of delegating to wrapped object.
Step 2: Identify correct delegation
Should call super().cost() to delegate to wrapped coffee object's cost method.
Final Answer:
Option A -> Option A
Quick Check:
Recursive call causes stack overflow, breaking decorator chain [OK]

Quick Trick: Decorator methods must delegate via super(), not self [OK]

Common Mistakes:

MISTAKES

Trap Explanation:

PITFALL

Calling self.cost() looks like recursion but is a subtle bug causing infinite loops.

Interviewer Note:

CONTEXT

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