Seems straightforward until you start thinking about what happens with missing keys, nested placeholders, or malformed delimiters.
Start by clarifying requirements: placeholder syntax, handling of missing keys, recursion, and escaping. Then propose a robust algorithm using regex or a parser, and discuss trade-offs like performance, security, and edge cases. Finally, outline a test plan and mention production considerations like logging and validation.
Pro tip: Demonstrate awareness of security risks like injection attacks and infinite recursion, and suggest safeguards such as depth limits and input sanitization. Also, mention that in a DevOps context, this function might be used for config templating, so idempotency and error handling are critical.
Ask about placeholder syntax (e.g., ${VAR}), whether substitution is recursive, how to handle missing keys (error, leave as-is, empty string), and if escaping is needed.
Choose an approach: simple string replacement, regex-based, or a parser for nested placeholders. Consider performance and complexity trade-offs.
Address missing keys, recursive substitution with cycle detection, special characters, and large inputs. Discuss error handling strategies.
Write clean, modular code with clear separation of concerns. Outline unit tests covering normal, edge, and error cases.
Mention logging, performance optimization (e.g., caching compiled regex), security (injection, DoS), and integration with DevOps tools like Kubernetes or Terraform.
AI-generated suggestions, not part of the candidate's original notes. May be inaccurate — verify before relying on them.