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packaging — PEP 440/508/517 version + tag utilities

Version: 26.0 Type: Pure Python SPM target: Bundled in Matplotlib (no standalone target) Auto-included by: Matplotlib, pip, importlib_metadata, and almost every Python distribution tool Total Python modules: 17 (15 top-level + 2 in licenses/)

The reference implementation of PEP 440 (version specifiers), PEP 508 (environment markers), PEP 517 (build-system spec), and the wheel/sdist tag system. If you've ever compared Version("3.14") to Version("3.5") or parsed "requests>=2.0,<3", this is the package that does it.

Bundled because basically every install/metadata tool needs it. On iOS its tags.py has explicit arm64_iphoneos / x86_64_iphonesimulator support — see the patch notes below.

Modules

Module What it does
packaging.__init__ Re-exports __version__; otherwise empty (submodule package)
packaging.version Version, InvalidVersion, parse — PEP 440 version objects with rich comparison
packaging.specifiers Specifier, SpecifierSet, InvalidSpecifier — ">=2.0,<3" parsing and Version in spec matching
packaging.requirements Requirement — full "name[extras] op version; marker" parser
packaging.markers Marker — environment markers (python_version >= '3.10', sys_platform == 'darwin')
packaging.tags Tag, sys_tags(), compatible_tags() — generates wheel-compatibility tags. iOS-aware: emits ios_<major>_<minor>_arm64_iphoneos tags
packaging.utils canonicalize_name, canonicalize_version, parse_wheel_filename, parse_sdist_filename
packaging.metadata Metadata, RawMetadata — METADATA / PKG-INFO field parsing
packaging.pylock PEP 751 pylock.toml model
packaging.licenses SPDX expression parsing (licenses/__init__.py, licenses/_spdx.py)
packaging._parser Hand-rolled parser shared by markers/specifiers/requirements
packaging._tokenizer Tokenizer feeding _parser
packaging._structures Infinity, NegativeInfinity sentinels used in version comparison
packaging._elffile Minimal ELF header reader (used by _manylinux)
packaging._manylinux manylinux glibc-version detection (Linux only; safe no-op on iOS)
packaging._musllinux musllinux libc-version detection (Linux only; safe no-op on iOS)

iOS-specific patches

None — packaging already ships native iOS support upstream. packaging.tags.ios_platforms() emits the correct ios_<major>_<minor>_arm64_iphoneos and *_iphonesimulator tags when sys.platform == "ios" (relies on platform.ios_ver() from Python 3.13+). _manylinux and _musllinux are no-ops on non-Linux platforms — they probe /etc/os-release and gracefully return empty tag sets.

Standalone example

from packaging.version import Version
from packaging.specifiers import SpecifierSet
from packaging.requirements import Requirement

v = Version("3.14.0a2")
print(v.is_prerelease, v.major, v.minor)   # True 3 14

spec = SpecifierSet(">=3.10,<4")
print(Version("3.14.0") in spec)           # True
print(Version("4.0.0") in spec)            # False

req = Requirement("torch[gpu] >=2.0; python_version >= '3.10'")
print(req.name, req.extras, req.specifier, req.marker)
# torch  {'gpu'}  >=2.0  python_version >= "3.10"

iOS-specific: inspect generated wheel tags

from packaging.tags import sys_tags
for tag in list(sys_tags())[:5]:
    print(tag)
# cp314-cp314-ios_17_0_arm64_iphoneos
# cp314-abi3-ios_17_0_arm64_iphoneos
# cp314-none-ios_17_0_arm64_iphoneos
# py314-none-ios_17_0_arm64_iphoneos
# py3-none-ios_17_0_arm64_iphoneos

See also