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Antra·Software Engineer·Technical Phone Screen·Intermediate

Intermediate
Jun 2026

Summary

Had a technical phone screen for a Software Engineer role at Antra that was basically one long OOP theory question dressed up as a design discussion. They wanted SOLID principles explained with actual examples, not just definitions, which I wasn't fully ready for.

Questions Asked (1)

Q1

Walk through each of the SOLID principles and give a concrete example or anti-pattern for each one.

Technical Trade-offsSystem Design
Author's notes

I knew the acronym cold but stumbled when they pushed for actual code examples.

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AI HintsAI Generated

Suggested Approach

Structure your answer by walking through each SOLID principle in order, briefly defining it and then giving a concrete example or anti-pattern from your experience. Keep each explanation concise and focused on how the principle improves maintainability and scalability, tying it back to real-world software engineering trade-offs.

Pro tip: Show maturity by acknowledging that SOLID principles are guidelines, not strict rules, and that over-applying them can lead to over-engineering; mention how you balance them with pragmatism and project constraints.

1. Introduce SOLID

Briefly state that SOLID is an acronym for five design principles that promote maintainable, scalable, and testable object-oriented code. Mention that you'll walk through each with an example.

2. Explain each principle with example/anti-pattern

For each principle (SRP, OCP, LSP, ISP, DIP), give a one-sentence definition, then a concrete example or anti-pattern. Keep each to 30-45 seconds.

3. Connect to trade-offs and real-world impact

After each example, briefly note how violating the principle leads to specific problems (e.g., fragile code, hard testing) and how adhering improves the system.

4. Summarize and emphasize pragmatism

Conclude by reiterating that SOLID helps manage complexity but should be applied judiciously; over-application can cause unnecessary abstraction.

Key Points to Mention

  • Single Responsibility Principle (SRP): A class should have one reason to change; anti-pattern: God object that handles multiple concerns.
  • Open/Closed Principle (OCP): Open for extension, closed for modification; example: using strategy pattern to add new behavior without altering existing code.
  • Liskov Substitution Principle (LSP): Subtypes must be substitutable for base types; anti-pattern: throwing exceptions in overridden methods that break client expectations.
  • Interface Segregation Principle (ISP): Clients shouldn't depend on interfaces they don't use; anti-pattern: fat interfaces forcing unnecessary implementations.
  • Dependency Inversion Principle (DIP): Depend on abstractions, not concretions; example: injecting a repository interface instead of a concrete database class.
  • Trade-offs: Over-application leads to over-engineering; balance with YAGNI and project needs.

AI-generated suggestions, not part of the candidate's original notes. May be inaccurate — verify before relying on them.