refactor: eliminate magic numbers by introducing named constants

[ogrew]

Summary

Replace hardcoded magic numbers with descriptive named constants to improve code maintainability and readability.

Changes Made

New Constants Added (src/const.lisp)

(defparameter +gif-fps-divider+ 2.0
  "Divider for GIF frame rate (output fps = source fps / divider)")

(defparameter +min-file-size+ 1024
  "Minimum file size in bytes to consider a file valid (not corrupt/incomplete)")

Magic Numbers Eliminated

1. GIF Frame Rate Calculation (src/ffmpeg.lisp:58)

   • Before: (/ fps 2.0)
   • After: (/ fps +gif-fps-divider+)
   • Context: GIF conversion uses half the source video's frame rate

2. File Size Threshold (src/ffmpeg.lisp:27)

   • Before: (< file-size 1024)
   • After: (< file-size +min-file-size+)
   • Context: Cleanup threshold for detecting incomplete/corrupted output files

Package Export (src/package.lisp)

• Added exports for both new constants to maintain API consistency

Benefits

• 🔍 Self-documenting code: Constants include descriptive names and docstrings
• 🔧 Easier maintenance: Centralized configuration values in const.lisp
• 📖 Improved readability: Clear intent behind numeric values
• 🎯 Consistency: Follows existing naming conventions (+constant-name+)
• ⚙️ Configurable: Easy to adjust thresholds without hunting through code

Implementation Notes

These constants were identified in docs/refactoring-tasks.md as part of the code quality improvement initiative. The values preserve existing behavior while making the code more maintainable.

Related Files

• src/const.lisp - New constant definitions
• src/package.lisp - Export declarations
• src/ffmpeg.lisp - Magic number replacements

Test plan

• Verify GIF conversion still works correctly: visp --gif test.mp4
• Confirm file cleanup behavior unchanged in error scenarios
• Run full test suite: make test
• Build verification: ros build visp.ros

This refactoring maintains identical functionality while improving code quality.

🤖 Generated with Claude Code