Cairo References and Snapshots

Overview

Explain when to pass by value, snapshot, or mutable reference, and how to read or mutate safely.

Quick Use

• Read references/references-snapshots.md before answering.
• Show the correct parameter form (value, @value, or ref value).
• Use *snapshot only for Copy types.

Response Checklist

• Use snapshots (@T) to read without moving ownership.
• Use ref when the callee must mutate and the caller must regain ownership.
• Remind that ref requires a mut variable at the call site.
• Call out that snapshots are immutable and cannot be mutated directly.

Example Requests

• "Why does passing this array move ownership?"
• "How do I modify a struct inside a function and keep it?"
• "What does @ mean in a type annotation?"

Cairo by Example

• Retaining Ownership
• Snapshots
• References