lib2to3 Module¶
⚠️ REMOVED IN PYTHON 3.13: The lib2to3 module and 2to3 tool were deprecated in Python 3.11 and removed in Python 3.13.
The lib2to3 module provided tools for converting Python 2 code to Python 3, using a refactoring framework with syntax tree transformations.
Complexity Reference¶
| Operation | Time | Space | Notes |
|---|---|---|---|
| Parse code | O(n) | O(n) | n = source length |
| Apply refactorings | O(n) | O(n) | n = tree nodes |
| Generate output | O(n) | O(n) | n = modified code |
Converting Python 2 to 3¶
Using 2to3 Tool¶
# Legacy command-line usage (Python <= 3.12)
2to3 -w script.py # Convert in place
2to3 -d script.py # Dry run (show diffs)
2to3 -f all script.py # Apply all fixers
2to3 -x print script.py # Skip print fixer
Programmatic Conversion¶
# Legacy API usage (Python <= 3.12)
from lib2to3 import refactor
# Create refactoring tool - O(1)
tool = refactor.RefactoringTool(
['lib2to3.fixes.fix_print',
'lib2to3.fixes.fix_imports']
)
# Refactor file - O(n)
refactored = tool.refactor_file('oldcode.py', write=True)