PCPP1 Best Practices And Coding Conventions — Timed 10 Questions

Question 1

Which practice is recommended when dealing with 'bare' except clauses in Python?

Accepted Answer

Always specify the exception type you intend to catch.. Bare 'except:' clauses catch SystemExit and KeyboardInterrupt, which can prevent the user from stopping a program.

Answer

Use bare 'except:' for performance optimization.

Answer

Use 'except Exception:' as the standard catch-all.

Answer

Use 'except:' but log the error immediately.

Question 2

When should you use absolute imports over relative imports in a large project?

Accepted Answer

Always, as they are PEP 8 recommended for clarity and robustness.. Absolute imports are recommended by PEP 8 because they are clearer and avoid ambiguity in complex package structures.

Answer

When the file is in the same directory.

Answer

Only if using Python 2.

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When performance is the main priority.

Question 3

You need to ensure your code is readable by other Python developers. Which naming style should be used for variable names?

Accepted Answer

snake_case.. PEP 8, the official Python style guide, mandates snake_case (all lowercase with underscores) for variable and function names. This convention is universally adopted across the Python standard library and community projects, making code immediately readable to other Python developers. Following PEP 8 ensures consistency and interoperability with tools like linters and formatters.

Answer

UPPER_SNAKE_CASE.

Answer

camelCase.

Answer

PascalCase.

Question 4

Which of the following is the correct way to handle whitespace around an operator according to PEP 8?

Accepted Answer

x = y + z. PEP 8 specifies that binary operators should be surrounded by exactly one space on each side when used in assignment or arithmetic expressions, so 'x = y + z' is the canonical form. This improves readability and is enforced by linters like flake8 and pycodestyle (E225, E226). The other options either omit spaces entirely or use multiple spaces, both of which violate the style guide.

Answer

x= y +z

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x  =  y  +  z

Answer

x=y+z

Question 5

Which THREE elements are essential for a good Python docstring?

Accepted Answer

A detailed description of the logic.. Option A is correct because a good docstring should include a detailed description of the logic, explaining how the object works beyond just its purpose. Option C is correct because a docstring must begin with a brief summary of the object's purpose, giving readers a quick understanding of what the function, class, or module does. Option D is correct because PEP 257 recommends a blank line after the summary line before any further elaboration, separating the one-line summary from the detailed description. Option B is not essential since docstrings describe behavior and usage, not an exhaustive list of variable types, which belongs in type hints or annotations. Option E is not appropriate because a docstring should not duplicate the full source code, which is already visible in the implementation.

Answer

A list of all possible variable types in the code.

Answer

The full source code of the function.

Question 6

You are writing a Python module that includes a function named `calculate_metrics`. The function accepts a required integer parameter `count`, an optional float parameter `threshold` with a default value, and an arbitrary number of additional keyword arguments. You want to add a docstring that follows the Google Python Style Guide. Which of the following is the correct way to document the parameters?

Accepted Answer

Args:
    count (int): The number of items to process.
    threshold (float, optional): The cutoff value. Defaults to 0.5.
    **kwargs: Additional keyword arguments.. The Google Python Style Guide specifies that function docstrings should include an 'Args:' section. Each parameter is listed with its name, type in parentheses, and a description. Optional parameters are indicated with ', optional' and their default value. Arbitrary keyword arguments (**kwargs) are listed without a type. The other options use different docstring conventions (NumPy, reST) or incorrectly type **kwargs.

Answer

Args:
    count (int): The number of items to process.
    threshold (float, optional): The cutoff value. Defaults to 0.5.
    kwargs (dict): Additional keyword arguments.

Answer

Parameters:
    count: int
        The number of items to process.
    threshold: float, optional
        The cutoff value. Defaults to 0.5.
    kwargs: dict
        Additional keyword arguments.

Answer

:param count: The number of items to process.
:type count: int
:param threshold: The cutoff value. Defaults to 0.5.
:type threshold: float, optional
:param kwargs: Additional keyword arguments.
:type kwargs: dict

Question 7

A development team is configuring a continuous integration pipeline for a Python package. They want to enforce PEP 8 style rules automatically. Which combination of tools should they integrate into the pipeline to check style and automatically fix common issues?

Accepted Answer

flake8 and black. flake8 and black are standard tools for PEP 8 enforcement. flake8 checks style and reports violations, while black automatically reformats code to a consistent style. This pairing allows CI pipelines to both detect and fix style issues, ensuring code adheres to PEP 8 with minimal manual intervention.

Answer

mypy and isort

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pycodestyle and yapf

Answer

pylint and autopep8

Question 8

A team is reviewing Python code for compliance with PEP 8's recommendations on comments. Which two of the following practices are correct according to PEP 8? (Choose two.)

Accepted Answer

Block comments should be indented to the same level as the code they describe.. PEP 8 recommends that comments be complete sentences with proper capitalization, and that block comments be indented to match the code they describe. Inline comments should be separated by at least two spaces, but that option was not selected as correct because the stem asks for two practices and the other correct options are more directly about comment content and placement.

Answer

Inline comments should be separated from the code by at least two spaces.

Answer

Comments should be written in English, unless coding for a non-English speaking audience.

Answer

Comments should be used to explain complex code, but also to disable code temporarily.

Question 9

A Python developer is reviewing a pull request and notices that a function is defined as `def calculate_total(items):` but the function returns a value that is never used. According to PEP 8, what is the recommended way to indicate that the return value is intentionally ignored?

Accepted Answer

Call the function without assigning its return value, and add a comment explaining why.. PEP 8 emphasizes code readability and explicitness. When a function's return value is not needed, simply calling the function without assignment is acceptable, especially if the function is invoked for its side effects. Adding a comment to explain why the return value is ignored improves clarity for future maintainers. This practice avoids unnecessary variable assignments and aligns with Python's philosophy of simplicity.

Answer

Prefix the function call with `# noqa` to suppress linter warnings.

Answer

Use the `del` statement on the return value immediately after the call.

Answer

Assign the return value to a variable named `_`.

Question 10

A developer is writing a context manager class to manage a database connection. They want to ensure that the connection is properly closed even if an exception occurs within the with block. Which method implementation correctly follows the context manager protocol?

Accepted Answer

__enter__ returns self and __exit__ closes the connection, returning False.. A context manager's __exit__ should release resources and return False to allow exceptions to propagate. Returning True suppresses exceptions, which is rarely desired. Not closing the resource or raising a new exception in __exit__ can mask errors or cause leaks. The correct implementation closes the connection and returns False.

Answer

__enter__ returns self and __exit__ closes the connection, returning True.

Answer

__enter__ returns the connection and __exit__ does not close it, returning False.

Answer

__enter__ returns the connection and __exit__ closes it, but raises an exception if any occurred.