- A
Override __new__ in DatabaseConnection to control instance creation and return the singleton from there, bypassing __init__ on subsequent calls.
Overriding __new__ allows you to return the existing instance before __init__ is called, preventing repeated initialization.
- B
Use the @staticmethod decorator on get_instance.
Why wrong: This does not affect the instantiation process or __init__ calls.
- C
Use a global variable instead of a class attribute to store the singleton.
Why wrong: A global variable does not prevent __init__ from being called when the class is instantiated.
- D
Move the connection initialization code out of __init__ and into a separate method that is called only once.
Why wrong: This would require changing all call sites to use the separate method, which is not a direct fix.
Quick Answer
The correct answer is to override the __new__ method in DatabaseConnection to control instance creation and return the singleton from there, bypassing __init__ on subsequent calls. This works because __new__ is responsible for creating the instance and is called before __init__; by checking the _instance attribute inside __new__, you can return the existing singleton without ever triggering __init__ again, which prevents the network connection from being established multiple times. On the Certified Associate Python Programmer PCAP exam, this tests your understanding of object lifecycle and the distinction between __new__ and __init__, a common trap being that a get_instance() class method alone still allows direct instantiation that calls __init__. The key insight is that __new__ is the true constructor in Python, while __init__ is only an initializer. Memory tip: think of __new__ as the bouncer who only lets one instance into the club, while __init__ is the coat-check that runs every time someone walks in—unless the bouncer hands them the same coat.
PCAP Object-Oriented Programming Practice Question
This PCAP practice question tests your understanding of object-oriented programming. Read the scenario carefully and evaluate each option against the stated constraints before committing to an answer. After answering, compare your reasoning against the explanation and wrong-answer breakdown below. Once you have made your selection, read the full explanation to reinforce the concept and understand why each distractor is designed to mislead on exam day.
An application uses a heavy-weight class DatabaseConnection that establishes a network connection upon instantiation. The class is used in multiple places, and the developer wants to ensure that only one instance of DatabaseConnection exists throughout the application. They implement a Singleton pattern using a class attribute _instance and a class method get_instance(). However, they notice that the network connection is being established multiple times. After debugging, they find that the singleton is not being enforced because the __init__ method is called every time the class is instantiated, even if the same instance is returned. They want to fix this so that the connection is established only once. Which modification should they make?
Answer choices
Why each option matters
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
Override __new__ in DatabaseConnection to control instance creation and return the singleton from there, bypassing __init__ on subsequent calls.
Option A is correct because overriding __new__ allows the developer to control instance creation at the lowest level. By checking if the singleton already exists in __new__, they can return the existing instance without calling __init__ again, thus preventing the network connection from being established multiple times. This is the standard Pythonic way to implement a singleton that avoids reinitialization.
Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✓
Override __new__ in DatabaseConnection to control instance creation and return the singleton from there, bypassing __init__ on subsequent calls.
Why this is correct
Overriding __new__ allows you to return the existing instance before __init__ is called, preventing repeated initialization.
Related concept
Read the scenario before looking for a memorised answer.
- ✗
Use the @staticmethod decorator on get_instance.
Why it's wrong here
This does not affect the instantiation process or __init__ calls.
- ✗
Use a global variable instead of a class attribute to store the singleton.
Why it's wrong here
A global variable does not prevent __init__ from being called when the class is instantiated.
- ✗
Move the connection initialization code out of __init__ and into a separate method that is called only once.
Why it's wrong here
This would require changing all call sites to use the separate method, which is not a direct fix.
Common exam traps
Common exam trap: answer the scenario, not the keyword
Python Institute often tests the distinction between instance creation (__new__) and instance initialization (__init__), trapping candidates who think that simply returning the same instance from a class method is enough to prevent reinitialization.
Detailed technical explanation
How to think about this question
In Python, __new__ is responsible for creating and returning a new instance of a class, while __init__ initializes that instance. By overriding __new__ to return the existing singleton instance, __init__ is automatically skipped because Python only calls __init__ on the object returned by __new__ if that object is a new instance of the class. This behavior is defined in CPython's object creation protocol and is critical for implementing singletons that require one-time initialization, such as a database connection pool or a configuration manager.
KKey Concepts to Remember
- Read the scenario before looking for a memorised answer.
- Find the constraint that changes the correct option.
- Eliminate answers that are true in general but not in this case.
TExam Day Tips
- Watch for words such as best, first, most likely and least administrative effort.
- Review why wrong options are wrong, not only why the correct option is correct.
Key takeaway
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Real-world example
How this comes up in practice
A healthcare organisation deploys an application with a public-facing web tier and a private database tier. The database subnet has no public IP and only accepts connections from the web tier's security group. Questions like this test whether you can design cloud network isolation using VNets/VPCs, subnets, and security group rules.
What to study next
Got this wrong? Here's your next step.
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FAQ
Questions learners often ask
What does this PCAP question test?
Object-Oriented Programming — This question tests Object-Oriented Programming — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: Override __new__ in DatabaseConnection to control instance creation and return the singleton from there, bypassing __init__ on subsequent calls. — Option A is correct because overriding __new__ allows the developer to control instance creation at the lowest level. By checking if the singleton already exists in __new__, they can return the existing instance without calling __init__ again, thus preventing the network connection from being established multiple times. This is the standard Pythonic way to implement a singleton that avoids reinitialization.
What should I do if I get this PCAP question wrong?
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
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Last reviewed: Jun 30, 2026
This PCAP practice question is part of Courseiva's free Python Institute certification practice question bank. Courseiva provides original exam-style practice questions with explanations, topic-based practice, mock exams, readiness tracking, and study analytics to help learners prepare for the PCAP exam.
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