Start by clarifying the requirements and defining the scope, then outline a robust parsing and comparison strategy that handles version normalization and constraint checking. Emphasize edge cases and error handling, and discuss how to extend to full PEP 440 compliance with a modular design.
Pro tip: Mention that you would use a well-tested library like packaging for production, but implement a simplified version to demonstrate understanding of the underlying algorithms and trade-offs.
Ask about the expected input formats, constraint operators (e.g., ==, >=, <), and whether pre-release versions should be included by default. Confirm error handling expectations for invalid inputs.
Outline a function to parse a version string into a tuple of integers and optional pre-release identifier, handling missing minor/patch by defaulting to zero. Normalize pre-release suffixes (e.g., 'a', 'b', 'rc') for comparison.
For each constraint specifier, parse the operator and version, then compare the normalized installed version. Combine multiple constraints with logical AND, and raise ValueError for invalid specifiers.
Enumerate boundary cases: equal versions, pre-release vs release, missing components, invalid strings, and multiple constraints. Explain how to test each systematically.
Describe how to support full PEP 440 syntax (e.g., ~=, ===, wildcards, local versions) by extending the parser and comparator. Discuss trade-offs between custom implementation and using libraries like packaging.
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