The correct approach is to override __new__ to raise an exception unless called from a classmethod factory. This works because __new__ is the lowest-level constructor in Python, responsible for actually creating the object before __init__ initializes it. By overriding __new__, you can inspect the call stack or check a flag set by the factory method, and if the call comes from direct instantiation rather than the factory, you raise an exception like TypeError. This prevents direct instantiation while still allowing the factory method to create instances, enforcing the factory pattern. On the PCAP exam, this tests your understanding of Python’s object creation lifecycle and the distinction between __new__ and __init__. A common trap is confusing __new__ with __init__—remember that __new__ controls creation, while __init__ only initializes. A useful memory tip: “__new__ is the gatekeeper; the factory holds the key.”
PCAP Object-Oriented Programming Practice Question
This PCAP practice question tests your understanding of object-oriented programming. The scenario asks you to isolate a root cause — eliminate options that address a different problem before choosing. 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.
A programmer wants to create a class that cannot be instantiated directly, only through a factory method. Which approach should be used?
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Override __new__ to raise an exception unless called from a classmethod factory.
Option C is correct because overriding `__new__` allows the programmer to control instance creation at the lowest level. By checking the call stack or a flag set by a classmethod factory, `__new__` can raise an exception when instantiation is attempted directly, while still allowing the factory method to create instances. This ensures the class cannot be instantiated directly, only through the designated factory.
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.
✗
Raise an exception in __init__ if called directly.
Why it's wrong here
__init__ is called after __new__, so the instance is already created.
✗
Define the class as abstract using ABC and @abstractmethod.
Why it's wrong here
Abstract classes can be instantiated if no abstract methods remain.
✓
Override __new__ to raise an exception unless called from a classmethod factory.
Why this is correct
__new__ controls instance creation; raising an exception prevents direct instantiation.
Related concept
Read the scenario before looking for a memorised answer.
✗
Use a metaclass to prevent instantiation.
Why it's wrong here
While possible, it's overkill and not a common pattern.
Common exam traps
Common exam trap: answer the scenario, not the keyword
Python Institute often tests the distinction between `__new__` and `__init__`, and the trap here is that candidates think raising an exception in `__init__` (Option A) is sufficient, not realizing that `__new__` has already created the object and the exception only prevents full initialization, not allocation.
Detailed technical explanation
How to think about this question
Under the hood, `__new__` is the first step in object creation, responsible for allocating memory and returning a new instance; by controlling it, you can gate creation before `__init__` is ever called. A common implementation uses a class-level flag (e.g., `_factory_called`) that the factory method sets before calling `cls.__new__`, and `__new__` checks this flag, raising an exception if it's not set. In real-world scenarios, this pattern is used for singleton or resource-pool classes where direct instantiation would bypass initialization logic or resource limits.
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 cloud solutions architect for a retail company is evaluating services for a new workload. The correct answer here reflects best practice for the specific scenario described — not a general cloud recommendation. Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option. Cloud exam questions reward reading the constraint carefully: the same technology can be right or wrong depending on the use case.
What to study next
Got this wrong? Here's your next step.
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
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__ to raise an exception unless called from a classmethod factory. — Option C is correct because overriding `__new__` allows the programmer to control instance creation at the lowest level. By checking the call stack or a flag set by a classmethod factory, `__new__` can raise an exception when instantiation is attempted directly, while still allowing the factory method to create instances. This ensures the class cannot be instantiated directly, only through the designated factory.
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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Question Discussion
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