[Solved] Examine this code snippet for a notification system:class Subject: def __init__(self): self.observers = set() def add_observer(self, observer): self.observers.add(observer) def notify_all(self):... | LLD

LLD - Design — Online Shopping Cart

Examine this code snippet for a notification system:

class Subject:
    def __init__(self):
        self.observers = set()
    def add_observer(self, observer):
        self.observers.add(observer)
    def notify_all(self):
        for observer in self.observers:
            observer.update()

What is the main issue that could cause notifications to fail?

AUsing a set for observers causes duplicate notifications

BObservers may not implement the update() method

Cnotify_all method should pass the subject as a parameter

Dadd_observer should use append instead of add

Step-by-Step Solution

Solution:

Step 1: Analyze observer collection type
Using a set is valid to avoid duplicates.
Step 2: Check notify_all implementation
notify_all calls observer.update() without parameters.
Step 3: Identify potential failure
If observers do not implement update(), calling update() will raise an error.
Final Answer:
Observers may not implement the update() method -> Option B
Quick Check:
Observer must implement update() [OK]

Quick Trick: Observers must implement update() method [OK]

Common Mistakes:

Assuming set causes duplicates
Forgetting to pass subject if required
Using append on a set collection

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More LLD Quizzes

Examine this code snippet for a notification system:

Step 1: Analyze observer collection type

Step 2: Check notify_all implementation

Step 3: Identify potential failure

Final Answer:

Quick Check:

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