Core behavior and first-principles view
File workflows in UI apps are trust-sensitive: users expect data safety, clear errors, and predictable behavior when paths fail or permissions change.
Key low-level points:
- Dialog selection is only the first step; path validity and access mode checks are still required.
- Serialization should be isolated from widget event handlers for maintainability.
- Safe-save strategy prevents corruption during interruption or crash.
Low-level model and equations
Estimated save duration:
Where:
- : bytes to write
- : effective write rate
How to build this correctly in practice
Validate selected path and open mode before any read/write operation.
Persist through temporary file then replace for critical documents.
Report actionable error messages (what failed and what user can do next).
Test cancel, permission-denied, missing-path, and malformed-content paths.
Common failure patterns and review checks
Never treat cancel as exceptional failure; it is normal user flow.
Do not overwrite existing files silently in data-loss-sensitive contexts.
Stream operation return values must be checked.
Encoding assumptions should be explicit for text files.
A robust open/save implementation protects user data and makes failure states recoverable.
