I started with the interface and factory pattern which felt right, but I got tripped up when they pushed on how a brand new format gets added without touching existing code.
Start by clarifying requirements and constraints, then design a class hierarchy with an abstract Parser base class and concrete subclasses for each format, using the Factory pattern for instantiation. Discuss extensibility through the Strategy pattern and plugin architecture, and address large files with streaming and malformed input with robust error handling and recovery strategies.
Pro tip: Emphasize that the parser should be decoupled from the data model—use a common intermediate representation (e.g., a record iterator) so downstream consumers are format-agnostic. Also, mention that malformed input handling should be configurable (fail-fast vs. skip-and-log) to suit different use cases.
Ask about expected file sizes, format variations, performance needs, and error tolerance to tailor the design. Confirm whether the system should support schema validation or just parsing.
Define an abstract Parser class with methods like parse(), and concrete subclasses (CSVParser, JSONParser, etc.). Use a Factory to create parsers based on file extension or content type.
Apply the Strategy pattern to encapsulate parsing algorithms, and allow new formats via a plugin system or registration mechanism. Discuss how to avoid modifying existing code when adding formats (Open/Closed Principle).
Use streaming or chunked parsing to avoid loading entire files into memory. Discuss trade-offs between memory usage and performance, and consider parallel processing for independent chunks.
Implement error handling strategies: fail-fast with detailed errors, skip-and-log, or attempt recovery. Make behavior configurable and ensure errors are reported with context (line number, column).
AI-generated suggestions, not part of the candidate's original notes. May be inaccurate — verify before relying on them.