__full__: Python 3.13 Changes

# Python 3.13 introduces __main__.py improvements if name == " main ": main() You can now use (in main .py): def main(): print("Running as main module") Python 3.13 automatically detects and runs main() in main .py No need for the if name guard in entry point modules 8. Security Enhancements import hashlib import ssl SHA-3 is now fully integrated and optimized def hash_demo(): data = b"Sensitive information"

print("✓ Running Python 3.13+")

async def main_new_way(): # Python 3.13 - same syntax, but ~10-15% faster # Task creation and scheduling overhead reduced async with asyncio.TaskGroup() as tg: tasks = [tg.create_task(process_item(i)) for i in range(1000)] return [task.result() for task in tasks] async def benchmark(): start = time.perf_counter() await main_old_way() old_time = time.perf_counter() - start python 3.13 changes

# SHA3-256 is now as fast as SHA-256 sha3_hash = hashlib.sha3_256(data).hexdigest() print(f"SHA3-256: sha3_hash[:16]...") # Python 3

# Dictionary creation and access dict_setup = """ d = {} for i in range(1000): d[i] = i * 2 """ 'u' string prefix (was deprecated since Python 3

# New hash algorithms with better security blake3_hash = hashlib.blake2b(data, digest_size=32).hexdigest() print(f"BLAKE2b: blake3_hash[:16]...") def ssl_improvements(): # Default minimum TLS version is now 1.3 context = ssl.create_default_context() print(f"Minimum TLS version: context.minimum_version") print(f"Maximum TLS version: context.maximum_version") 9. Removal of Deprecated Features # Things that no longer work in Python 3.13: 1. 'u' string prefix (was deprecated since Python 3.3) u"text" # SyntaxError in 3.13 2. crypt module removed (use hashlib or passlib instead) import crypt # ModuleNotFoundError 3. 2to3 tool removed (use pyupgrade or modernize) 4. Old-style datetime formatting from datetime import datetime dt = datetime.now() dt.strftime("%Y-%m-%d") # Still works But %z without colon is deprecated 5. asyncio.coroutine decorator removed (use async/await) @asyncio.coroutine # AttributeError def old_style(): pass 10. New Environment Variables # Enable experimental JIT compiler export PYTHON_JIT=1 Configure JIT threshold (when to compile hot code) export PYTHON_JIT_THRESHOLD=1000 Disable new error message suggestions (for CI) export PYTHON_COLORS=0 Configure asyncio debug level export PYTHONASYNCIODEBUG=2 Migration Checklist # Check your code for compatibility with Python 3.13 import sys import warnings