How do you design ABI-stable C++ APIs?
PICTURE THIS: RAG CHATBOT
Simple meaning
Use pimpl, C interfaces, or carefully versioned shared libs.
WHY — Modern instead of guessing?
Why interviewers care about Modern:
question about Modern.
trade-offs, and what you would actually do on a C++ project - not buzzwords.
Name the idea, why it exists, then one short example.
End with when you use it and one common pitfall.
STEPS — What happens step by step?
Before you speak the answer, walk the interviewer through these steps:
- 1Use pimpl, C interfaces,
or carefully versioned shared libs.
- 2Exposing STL types across
boundaries is fragile.
- 3How it works
Document supported compilers.
- 4Give an example
One tiny concrete case you can say aloud.
- 5Common mistake
What juniors usually get wrong.
- 6Close
When you pick this over the alternative.
EXAMPLE — See it in action
Here's a short line you can speak, broken into clear beats:
Note: Adapt this scaffold to your own project — keep it under 60–90 seconds.
Key takeaway
Use pimpl, C interfaces, or carefully versioned shared libs. Exposing STL types across boundaries is fragile.