{"id":5017,"library":"pycnite","title":"Python bytecode utilities","description":"Pycnite is a collection of utilities for working with compiled Python bytecode. This library provides pure Python, versioned parsers for the .pyc format, enabling tools that work with bytecode to support different host and target Python versions. It currently supports target Python versions 3.8 through 3.12.","status":"active","version":"2024.7.31","language":"en","source_language":"en","source_url":"https://github.com/google/pycnite","tags":["bytecode","python-internals","reverse-engineering","tooling","pyc-parser"],"install":[{"cmd":"pip install pycnite","lang":"bash","label":"Install latest version"}],"dependencies":[],"imports":[{"note":"The primary module for .pyc file parsing.","symbol":"pyc","correct":"from pycnite import pyc"},{"note":"Contains utilities for bytecode manipulation and representation.","symbol":"bytecode","correct":"from pycnite import bytecode"}],"quickstart":{"code":"import os\nimport py_compile\nimport tempfile\n\n# Create a dummy Python file\ndummy_py_content = '''\ndef greet(name):\n    message = f\"Hello, {name}!\"\n    return message\n\nresult = greet(\"World\")\n'''\n\n# Use tempfile to create and manage temporary files\nwith tempfile.TemporaryDirectory() as tmpdir:\n    dummy_py_path = os.path.join(tmpdir, 'dummy_module.py')\n    dummy_pyc_path = os.path.join(tmpdir, '__pycache__', 'dummy_module.cpython-310.pyc') # Adjust for your Python version\n\n    with open(dummy_py_path, 'w') as f:\n        f.write(dummy_py_content)\n\n    # Compile the .py file to .pyc\n    # py_compile automatically creates __pycache__ and the .pyc file\n    py_compile.compile(dummy_py_path, cfile=dummy_pyc_path, doraise=True)\n\n    print(f\"Generated .pyc file at: {dummy_pyc_path}\")\n    \n    try:\n        from pycnite import pyc\n\n        # Load the .pyc file using pycnite\n        # You may need to specify the Python version if pycnite can't infer it\n        # For example, pyc.load_pyc(dummy_pyc_path, python_version=(3, 10))\n        pyc_file = pyc.load_pyc(dummy_pyc_path)\n\n        print(f\"\\nLoaded .pyc file successfully. Python version: {pyc_file.version}\")\n        print(f\"Magic number: {hex(pyc_file.magic)}\")\n\n        # Accessing the code object (example for the module's code object)\n        code_obj = pyc_file.code\n        print(f\"\\nCode object name: {code_obj.co_name}\")\n        print(f\"Number of arguments: {code_obj.co_argcount}\")\n        print(f\"Constants: {code_obj.co_consts}\")\n        print(f\"Names used: {code_obj.co_names}\")\n        # print(f\"Disassembled bytecode:\\n{code_obj.dis()}\") # Requires 'dis' module and pycnite's dis method\n\n    except ImportError:\n        print(\"\\nPycnite not installed. Skipping pycnite specific checks.\")\n    except Exception as e:\n        print(f\"\\nError loading .pyc with pycnite: {e}\")\n","lang":"python","description":"This quickstart demonstrates how to programmatically compile a Python source file into a .pyc file using the standard `py_compile` module, and then use `pycnite` to load and inspect the compiled bytecode. This allows for programmatic analysis of Python's low-level execution instructions and metadata contained within .pyc files. Ensure the `dummy_pyc_path` matches the actual filename convention for your Python version (e.g., `cpython-310.pyc` for Python 3.10)."},"warnings":[{"fix":"Always pin to a specific version (`pycnite==X.Y.Z`) and test thoroughly when upgrading to new releases.","message":"Pycnite is currently in 'Development Status :: 3 - Alpha'. This means the API might not be stable, and breaking changes could occur in future versions without extensive prior notice.","severity":"gotcha","affected_versions":"All versions"},{"fix":"Consult pycnite's documentation or source code for explicitly supported Python target versions. Report any issues for unsupported versions to the maintainers.","message":"The `.pyc` file format is an implementation detail of CPython and can change between Python versions, even minor ones. While pycnite aims to support multiple versions, unexpected behavior may occur with new or unsupported Python versions.","severity":"gotcha","affected_versions":"All versions"}],"env_vars":null,"last_verified":"2026-04-12T00:00:00.000Z","next_check":"2026-07-11T00:00:00.000Z"}