The answer is to define a list variable named `__all__` containing the string names `'Circle'` and `'Square'`. This works because the `__all__` variable in a Python module explicitly controls which names are exported when a client uses `from module import *`, acting as a whitelist that restricts wildcard imports to only the specified identifiers. On the Certified Associate Python Programmer PCAP exam, this concept tests your understanding of module encapsulation and namespace control, often appearing as a distractor where candidates confuse `__all__` with `__init__` or assume all public names are automatically exported. A common trap is forgetting that `__all__` must be a list of strings, not the objects themselves, and that it only affects `from module import *`, not direct imports like `from module import Triangle`. Memory tip: think of `__all__` as the module’s “bouncer” at the door—only the names on the list get into the wildcard party.
PCAP Modules and Packages Practice Question
This PCAP practice question tests your understanding of modules and packages. 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.
A module 'shapes.py' defines several classes: Circle, Square, Triangle. The developer wants to allow users to import only Circle and Square when they use 'from shapes import *'. Which mechanism 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
✓
Define a list variable named __all__ containing the string names 'Circle' and 'Square'.
Option D is correct because the `__all__` variable in a module explicitly controls which names are exported when a client uses `from shapes import *`. By setting `__all__ = ['Circle', 'Square']`, only those two classes are imported, while `Triangle` is excluded. This is the standard Python mechanism for restricting wildcard imports.
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.
✗
Prefix the Triangle class with an underscore to make it private.
Why it's wrong here
Underscore indicates private but does not affect 'import *' by default; __all__ is still needed.
✗
Use the import_explicit function.
Why it's wrong here
No such built-in function.
✗
Create an __init__.py file in the same directory.
Why it's wrong here
__init__.py is for packages, not single module files.
✓
Define a list variable named __all__ containing the string names 'Circle' and 'Square'.
Why this is correct
__all__ explicitly lists names to export.
Related concept
Read the scenario before looking for a memorised answer.
Common exam traps
Common exam trap: answer the scenario, not the keyword
Python Institute often tests the misconception that an underscore prefix makes a name truly private or that an `__init__.py` file alone controls wildcard imports from a single module, leading candidates to choose A or C instead of the correct `__all__` mechanism.
Detailed technical explanation
How to think about this question
The `__all__` variable must be a list of strings (or tuple) at the module level; if it is not defined, `from module import *` imports all names that do not start with an underscore. A subtle behavior: if `__all__` contains a name that does not exist in the module, Python raises a `NameError` at import time. In real-world code, `__all__` is often used in library packages to expose a clean public API while hiding implementation details.
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.
Modules and Packages — This question tests Modules and Packages — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: Define a list variable named __all__ containing the string names 'Circle' and 'Square'. — Option D is correct because the `__all__` variable in a module explicitly controls which names are exported when a client uses `from shapes import *`. By setting `__all__ = ['Circle', 'Square']`, only those two classes are imported, while `Triangle` is excluded. This is the standard Python mechanism for restricting wildcard imports.
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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