PCPP1 Best Practices And Coding Conventions — 25 Questions

Question 1

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 2

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 3

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.

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Use bare 'except:' for performance optimization.

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

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Use 'except:' but log the error immediately.

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 (context manager) ensures that cleanup code is executed even if an exception occurs.

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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 exceptions should inherit from the built-in Exception class to ensure they are catchable by standard error handlers.

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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 requires explicit listing of types in the Args section to improve readability for static analysis tools.

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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 states that spaces are the preferred indentation method over tabs to ensure cross-platform consistency.

Answer

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.

Answer

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 fundamentally insecure; using secure formats like JSON is the only way to avoid code injection during deserialization.

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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

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.

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When the file is in the same directory.

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Only if using Python 2.

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When performance is the main priority.

Question 15

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 prescribes snake_case (lowercase with underscores) for variable and function names.

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UPPER_SNAKE_CASE.

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camelCase.

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PascalCase.

Question 16

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 dictates surrounding operators with a single space on both sides.

Answer

x= y +z

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x  =  y  +  z

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x=y+z

Question 17

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', which encourages using try-except blocks instead of pre-checking states.

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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 18

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.

Question 19

Which comment style is preferred for block comments in Python?

Accepted Answer

Each line starting with a single '#' and a space.. Block comments should consist of paragraphs of text, each starting with a # and a single space.

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Using a string literal (triple quotes) at the top level.

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Using block comments inside a single line.

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Using a single '#' at the end of every line.

Question 20

You are implementing a custom context manager using a class. Which methods must be implemented to support the 'with' statement?

Accepted Answer

__enter__ and __exit__.. A context manager requires `__enter__` to set up the resource and `__exit__` to handle cleanup.

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__setup__ and __teardown__.

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__open__ and __close__.

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__init__ and __del__.