PCPP1 Best Practices And Coding Conventions Practice Test 2 — 15 Questions

Question 1

A developer is writing a Python function that takes several parameters. They want to follow PEP 8 recommendations for breaking long lines. Which of the following is the preferred way to align arguments when a function call spans multiple lines?

Choose an answer to begin — your selection is scored in the full session.

Accepted Answer

Align the arguments vertically under the first argument, using opening delimiter alignment.. PEP 8 recommends using opening delimiter alignment for function calls that span multiple lines: the first argument goes on the same line as the opening parenthesis, and subsequent arguments align vertically under it. This style is clear and consistent. Alternatively, a hanging indent can be used, but it must be distinguishable from the block indentation. The key is to avoid backslashes and ensure readability.

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Place each argument on a new line, indented by exactly 8 spaces from the start of the line.

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Use a hanging indent with a fixed number of spaces (e.g., 4) for all continuation lines.

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Use backslashes to continue the line and align arguments under the first argument.

Question 2

According to PEP 257, what is the standard format for a single-line docstring?

Accepted Answer

Use triple quotes and keep the summary on the same line, ending with a period.. A single-line docstring should be on the same line as the opening triple quotes, ending with a period.

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Use a single quote for the entire block.

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The docstring should span three lines including the summary.

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The summary should start on the next line.

Question 3

When naming a constant in Python, which convention does PEP 8 recommend?

Accepted Answer

UPPER_CASE_WITH_UNDERSCORES.. Constants should be named using all capital letters with underscores to separate words.

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PascalCase.

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snake_case.

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CamelCase.

Question 4

You are debugging a legacy application and need to ensure that resources like file handles are always closed. Which construct is preferred?

Accepted Answer

Use a context manager with the 'with' statement.. The 'with' statement invokes a context manager, which guarantees that the __exit__ method runs and closes the file handle even if an exception occurs inside the block. This is the idiomatic, preferred Python construct for deterministic resource cleanup. It is cleaner and safer than manual try/finally code.

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Wrap the file operation in a try-except block.

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Manually call file.close() in a finally block.

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Rely on the garbage collector to close the handle.

Question 5

You are writing a library that expects a custom exception. Which practice aligns best with Python's exception handling hierarchy?

Accepted Answer

Inherit from Exception.. Custom application exceptions should inherit from Exception, which is the base class for all non-system-exiting exceptions and is intended for user-defined errors. Inheriting from Exception ensures the exception is caught by normal 'except Exception' handlers and does not interfere with interpreter-level control flow. This is the standard practice recommended by PEP 8 and the Python documentation.

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Use a mixin class without inheritance.

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Inherit from StandardError.

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Inherit from BaseException.

Question 6

When implementing secure coding practices in a web-facing Python application, how should you handle raw user input to prevent command injection?

Accepted Answer

Pass input arguments as a list to subprocess.run(args, shell=False).. Using the 'subprocess' module with 'shell=False' (the default) prevents the shell from interpreting user-provided strings as commands.

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Pass the entire input string to os.system().

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Concatenate the input string into a shell command for execution.

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Sanitize input using a custom regex to remove special characters.

Question 7

When documenting a complex function, which approach is most compliant with Google Style Python Docstrings regarding parameter types?

Accepted Answer

Use the 'Args:' section followed by the parameter name, type, and description.. Google Style Python Docstrings require an 'Args:' section where each parameter is listed with its name, type, and description in the format 'name (type): description'. This makes the function's interface self-documenting and consistent with tools like Sphinx Napoleon that parse Google-style docstrings.

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Embed the types directly in the function name.

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Include type hints in the docstring but omit them from the function signature.

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Avoid documenting types to prevent redundancy with type hints.

Question 8

In a team environment, which PEP 8 guideline should be applied to maintain consistent indentation when mixing spaces and tabs?

Accepted Answer

Use spaces exclusively for indentation.. PEP 8 explicitly recommends using spaces exclusively for indentation, with four spaces per indentation level. This avoids the ambiguity and inconsistency that arises when tabs and spaces are mixed, which can lead to Python interpreting indentation differently across editors and causing IndentationError or TabError. Using spaces ensures that code looks the same regardless of editor tab width settings.

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Use tabs exclusively, as they are more efficient for file size.

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Always use a combination of tabs and spaces to allow personal editor configuration.

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Default to the indentation used by the first author of the module.

Question 9

According to PEP 8, what is the maximum recommended length for a line of code?

Accepted Answer

79 characters.. PEP 8 suggests limiting lines to 79 characters to allow multiple files to be opened side-by-side.

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80 characters.

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No limit.

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120 characters.

Question 10

When designing a public API, how should you signal that a method is for internal use only?

Accepted Answer

By prepending a single underscore.. Prefixing a name with a single underscore is the conventional way to indicate internal use.

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By raising a warning if called externally.

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By adding a comment like '# INTERNAL'.

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By using all caps.

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By suffixing with an underscore.

Question 11

You are refactoring code that performs sensitive operations. Which of the following is the most secure practice for handling secret keys?

Accepted Answer

Use environment variables to store sensitive configuration.. Hardcoding secrets is a major security vulnerability; using environment variables is the industry standard.

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Encrypt the secrets and store them as constants in a module.

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Store secrets in a private class attribute.

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Hardcode them as strings inside a 'config.py' file and ignore it in Git.

Question 12

A script processes data from untrusted sources. Which technique best mitigates 'pickle' deserialization vulnerabilities?

Accepted Answer

Use an alternative format like JSON or XML for serialization.. The pickle module is inherently unsafe for untrusted data because unpickling executes arbitrary code via the __reduce__ method during object reconstruction. The only reliable mitigation is to avoid pickle entirely for untrusted input and use a data-only format like JSON or XML, which cannot execute code during parsing. JSON/XML parsers only construct primitive data types (dicts, lists, strings, numbers), eliminating the remote code execution vector.

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Only unpickle from files with a specific extension.

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Wrap the unpickling in a try-except block.

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Use 'pickle.load()' with a restricted whitelist of modules.

Question 13

What is the primary benefit of using 'logging' over 'print' statements for application diagnostics?

Accepted Answer

It allows setting severity levels and routing logs to different handlers.. The 'logging' module provides granular control over levels, destinations, and output formatting without changing the source code.

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It is faster for small scripts.

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It prevents the application from crashing on errors.

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It automatically cleans up log files.

Question 14

In the context of writing robust error handling, what is the 'EAFP' principle?

Accepted Answer

Easier to Ask for Forgiveness than Permission.. EAFP stands for 'Easier to Ask for Forgiveness than Permission,' a Python coding philosophy that encourages attempting an operation and catching exceptions if it fails, rather than checking preconditions beforehand. In practice, this means using try/except blocks around code that might raise errors (e.g., accessing a dictionary key or opening a file) instead of using if statements to verify conditions first. This approach aligns with Python's dynamic nature and often results in cleaner, faster code because it avoids redundant checks and race conditions.

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Ensure All Functions Pass.

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Exit All Files Properly.

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Evaluate All Faults Promptly.

Question 15

When writing a library, what is the best practice for documenting the usage of a function?

Accepted Answer

Use docstrings to provide a clear summary and usage details.. Docstrings provide the most standard and accessible form of documentation that can be integrated with tools like Sphinx.

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Include the documentation as comments above the function definition.

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Provide usage examples in the 'README.md' file only.

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Wait for users to ask for documentation.