20 Mar 2024



  • Make MetadataPathFinder.find_distributions a classmethod for consistency with CPython. Closes #484. (#484)

  • Allow MetadataPathFinder.invalidate_caches to be called as a classmethod.


No significant changes.



  • Corrected the interface for SimplePath to encompass the expectations of locate_file and PackagePath.

  • Fixed type annotations to allow strings.


Deprecations and Removals#

  • Removed EntryPoint access by numeric index (tuple behavior).



  • Added Distribution.origin supplying the direct_url.json in a SimpleNamespace. (#404)



  • Added diagnose script. (#461)



  • Added EntryPoints.__repr__ (#473)



  • Require Python 3.8 or later.


  • #453: When inferring top-level names that are importable for distributions in package_distributions, now symlinks to other directories are honored.


  • #449: Expanded type annotations.


  • python/cpython#103661: Removed excess error suppression in _read_files_egginfo_installed and fixed path handling on Windows.


  • #422: Removed ABC metaclass from Distribution and instead deprecated construction of Distribution objects without concrete methods.


  • Updated docs with tweaks from upstream CPython.


  • Consolidated some behaviors in tests around _path.

  • Added type annotation for Distribution.read_text.


  • #115: Support installed-files.txt for Distribution.files when present.


  • #442: Fixed issue introduced in v6.1.0 where non-importable names (metadata dirs) began appearing in packages_distributions.


  • #384: PackageMetadata now stipulates an additional get method allowing for easy querying of metadata keys that may not be present.


  • #428: packages_distributions now honors packages and modules with Python modules that not .py sources (e.g. .pyc, .so).


  • #434: Expand protocol for PackageMetadata.get_all to match the upstream implementation of email.message.Message.get_all in python/typeshed#9620.


  • #419: Declared Distribution as an abstract class, enforcing definition of abstract methods in instantiated subclasses. It’s no longer possible to instantiate a Distribution or any subclasses unless they define the abstract methods.

    Please comment in the issue if this change breaks any projects. This change will likely be rolled back if it causes significant disruption.


  • #371: Deprecated expectation that PackageMetadata.__getitem__ will return None for missing keys. In the future, it will raise a KeyError.


  • #415: Instrument SimplePath with generic support.


  • #97, #284, #300: Removed compatibility shims for deprecated entry point interfaces.


  • #396: Added compatibility for PathDistributions originating from Python 3.8 and 3.9.


  • py-93259: Now raise ValueError when None or an empty string are passed to Distribution.from_name (and other callers).


  • #379: In PathDistribution._name_from_stem, avoid including parts of the extension in the result.

  • #381: In PathDistribution._normalized_name, ensure names loaded from the stem of the filename are also normalized, ensuring duplicate entry points by packages varying only by non-normalized name are hidden.

Note (#459): This change had a backward-incompatible effect for any installers that created metadata in the filesystem with dashes in the package names (not replaced by underscores).


  • #372: Removed cast of path items in FastPath, not needed.


  • #369: Fixed bug where EntryPoint.extras was returning match objects and not the extras strings.


  • #367: In Distribution.requires for egg-info, if requires.txt is empty, return an empty list.


  • bpo-46246: Added __slots__ to EntryPoints.


  • #365 and bpo-46546: Avoid leaking method_name in DeprecatedList.



  • #361: Avoid potential REDoS in EntryPoint.pattern.


  • #354: Removed Distribution._local factory. This functionality was created as a demonstration of the possible implementation. Now, the pep517 package provides this functionality directly through pep517.meta.load.


  • Require Python 3.7 or later.


  • #357: Fixed requirement generation from egg-info when a URL requirement is given.



  • #353: Fixed discovery of distributions when path is empty.


  • #348: Restored support for EntryPoint access by item, deprecating support in the process. Users are advised to use direct member access instead of item-based access:

    - ep[0] -> ep.name
    - ep[1] -> ep.value
    - ep[2] -> ep.group
    - ep[:] -> ep.name, ep.value, ep.group


  • #337: Rewrote EntryPoint as a simple class, still immutable and still with the attributes, but without any expectation for namedtuple functionality such as _asdict.


  • #344: Fixed regression in packages_distributions when neither top-level.txt nor a files manifest is present.


  • #330: In packages_distributions, now infer top-level names from .files() when a top-level.txt (Setuptools-specific metadata) is not present.


  • #334: Correct SimplePath protocol to match pathlib protocol for __truediv__.


  • Moved workaround for #327 to _compat module.


  • bpo-44784: Avoid errors in test suite when DeprecationWarnings are treated as errors.


  • #327: Deprecation warnings now honor call stack variance on PyPy.


  • #326: Performance tests now rely on pytest-perf. To disable these tests, which require network access and a git checkout, pass -p no:perf to pytest.


  • #319: Remove SelectableGroups deprecation exception for flake8.


  • #300: Restore compatibility in the result from Distribution.entry_points (EntryPoints) to honor expectations in older implementations and issuing deprecation warnings for these cases:

    • EntryPoints objects are once again mutable, allowing for sort() and other list-based mutation operations. Avoid deprecation warnings by casting to a mutable sequence (e.g. list(dist.entry_points).sort()).

    • EntryPoints results once again allow for access by index. To avoid deprecation warnings, cast the result to a Sequence first (e.g. tuple(dist.entry_points)[0]).


  • #320: Fix issue where normalized name for eggs was incorrectly solicited, leading to metadata being unavailable for eggs.


  • #317: De-duplication of distributions no longer requires loading the full metadata for PathDistribution objects, entry point loading performance by ~10x.


  • Prefer f-strings to .format calls.


  • #312: Add support for metadata 2.2 (Dynamic field).

  • #315: Add SimplePath protocol for interface clarity in PathDistribution.


  • #306: Clearer guidance about compatibility in readme.


  • #304: PackageMetadata as returned by metadata() and Distribution.metadata() now provides normalized metadata honoring PEP 566:

    • If a long description is provided in the payload of the RFC 822 value, it can be retrieved as the Description field.

    • Any multi-line values in the metadata will be returned as such.

    • For any multi-line values, line continuation characters are removed. This backward-incompatible change means that any projects relying on the RFC 822 line continuation characters being present must be tolerant to them having been removed.

    • Add a json property that provides the metadata converted to a JSON-compatible form per PEP 566.


  • Minor tweaks from CPython.


  • #295: Internal refactoring to unify section parsing logic.


  • #296: Exclude ‘prepare’ package.

  • #297: Fix ValueError when entry points contains comments.


  • Use of Mapping (dict) interfaces on SelectableGroups is now flagged as deprecated. Instead, users are advised to use the select interface for future compatibility.

    Suppress the warning with this filter: ignore:SelectableGroups dict interface.

    Or with this invocation in the Python environment: warnings.filterwarnings('ignore', 'SelectableGroups dict interface').

    Preferably, switch to the select interface introduced in 3.7.0. See the entry points documentation and changelog for the 3.6 release below for more detail.

    For some use-cases, especially those that rely on importlib.metadata in Python 3.8 and 3.9 or those relying on older importlib_metadata (especially on Python 3.5 and earlier), backports.entry_points_selectable was created to ease the transition. Please have a look at that project if simply relying on importlib_metadata 3.6+ is not straightforward. Background in #298.

  • #283: Entry point parsing no longer relies on ConfigParser and instead uses a custom, one-pass parser to load the config, resulting in a ~20% performance improvement when loading entry points.


  • #293: Re-enabled lazy evaluation of path lookup through a FreezableDefaultDict.


  • #293: Workaround for error in distribution search.


  • #290: Add mtime-based caching for FastPath and its lookups, dramatically increasing performance for repeated distribution lookups.


  • Docs enhancements and cleanup following review in GH-24782.


  • Cleaned up cruft in entry_points docstring.


  • Internal refactoring to facilitate entry_points() -> dict deprecation.


  • #131: Added packages_distributions to conveniently resolve a top-level package or module to its distribution(s).


  • #284: Introduces new EntryPoints object, a tuple of EntryPoint objects but with convenience properties for selecting and inspecting the results:

    • .select() accepts group or name keyword parameters and returns a new EntryPoints tuple with only those that match the selection.

    • .groups property presents all of the group names.

    • .names property presents the names of the entry points.

    • Item access (e.g. eps[name]) retrieves a single entry point by name.

    entry_points now accepts “selection parameters”, same as EntryPoint.select().

    entry_points() now provides a future-compatible SelectableGroups object that supplies the above interface (except item access) but remains a dict for compatibility.

    In the future, entry_points() will return an EntryPoints object for all entry points.

    If passing selection parameters to entry_points, the future behavior is invoked and an EntryPoints is the result.

  • #284: Construction of entry points using dict([EntryPoint, ...]) is now deprecated and raises an appropriate DeprecationWarning and will be removed in a future version.

  • #300: Distribution.entry_points now presents as an EntryPoints object and access by index is no longer allowed. If access by index is required, cast to a sequence first.


  • #280: entry_points now only returns entry points for unique distributions (by name).


  • #10: Project now declares itself as being typed.

  • #272: Additional performance enhancements to distribution discovery.

  • #111: For PyPA projects, add test ensuring that MetadataPathFinder._search_paths honors the needed interface. Method is still private.


  • #265: EntryPoint objects now expose a .dist object referencing the Distribution when constructed from a Distribution.


  • The object returned by metadata() now has a formally-defined protocol called PackageMetadata with declared support for the .get_all() method. Fixes #126.



  • #261: Restored compatibility for package discovery for metadata without version in the name and for legacy eggs.


  • Merge with 2.1.0.



  • Require Python 3.6 or later.


  • importlib_metadata no longer presents a __version__ attribute. Consumers wishing to resolve the version of the package should query it directly with importlib_metadata.version('importlib-metadata'). Closes #71.


  • PathNotFoundError now has a custom __str__ mentioning “package metadata” being missing to help guide users to the cause when the package is installed but no metadata is present. Closes #124.


  • Added Distribution._local() as a provisional demonstration of how to load metadata for a local package. Implicitly requires that pep517 is installed. Ref #42.

  • Ensure inputs to FastPath are Unicode. Closes #121.

  • Tests now rely on importlib.resources.files (and backport) instead of the older path function.

  • Support any iterable from find_distributions. Closes #122.


  • Added module and attr attributes to EntryPoint


  • Fix redundant entries from FastPath.zip_children. Closes #117.


  • Improve reliability and consistency of compatibility imports for contextlib and pathlib when running tests. Closes #116.


  • Additional performance optimizations in FastPath now saves an additional 20% on a typical call.

  • Correct for issue where PyOxidizer finder has no __module__ attribute. Closes #110.


  • Through careful optimization, distribution() is 3-4x faster. Thanks to Antony Lee for the contribution. Closes #95.

  • When searching through sys.path, if any error occurs attempting to list a path entry, that entry is skipped, making the system much more lenient to errors. Closes #94.


  • Improve custom finders documentation. Closes #105.


  • Once again, drop support for Python 3.4. Ref #104.


  • Restored support for Python 3.4 due to improper version compatibility declarations in the v1.1.0 and v1.1.1 releases. Closes #104.


  • Repaired project metadata to correctly declare the python_requires directive. Closes #103.


  • Fixed repr(EntryPoint) on PyPy 3 also. Closes #102.


  • Dropped support for Python 3.4.

  • EntryPoints are now pickleable. Closes #96.

  • Fixed repr(EntryPoint) on PyPy 2. Closes #97.


  • Project adopts semver for versioning.

  • Removed compatibility shim introduced in 0.23.

  • For better compatibility with the stdlib implementation and to avoid the same distributions being discovered by the stdlib and backport implementations, the backport now disables the stdlib DistributionFinder during initialization (import time). Closes #91 and closes #100.


  • Added a compatibility shim to prevent failures on beta releases of Python before the signature changed to accept the “context” parameter on find_distributions. This workaround will have a limited lifespan, not to extend beyond release of Python 3.8 final.


  • Renamed package parameter to distribution_name as recommended in the following functions: distribution, metadata, version, files, and requires. This backward-incompatible change is expected to have little impact as these functions are assumed to be primarily used with positional parameters.


  • importlib.metadata now exposes the DistributionFinder metaclass and references it in the docs for extending the search algorithm.

  • Add Distribution.at for constructing a Distribution object from a known metadata directory on the file system. Closes #80.

  • Distribution finders now receive a context object that supplies .path and .name properties. This change introduces a fundamental backward incompatibility for any projects implementing a find_distributions method on a MetaPathFinder. This new layer of abstraction allows this context to be supplied directly or constructed on demand and opens the opportunity for a find_distributions method to solicit additional context from the caller. Closes #85.


  • Clarify in the docs that calls to .files could return None when the metadata is not present. Closes #69.

  • Return all requirements and not just the first for dist-info packages. Closes #67.


  • Restrain over-eager egg metadata resolution.

  • Add support for entry points with colons in the name. Closes #75.


  • Parse entry points case sensitively. Closes #68

  • Add a version constraint on the backport configparser package. Closes #66


  • Fix a permission problem in the tests on Windows.


  • Don’t crash if there exists an EGG-INFO directory on sys.path.


  • Fix documentation.


  • Removed local_distribution function from the API. This backward-incompatible change removes this behavior summarily. Projects should remove their reliance on this behavior. A replacement behavior is under review in the pep517 project. Closes #42.


  • Update docstrings to match PEP 8. Closes #63.

  • Merged modules into one module. Closes #62.


  • Add support for eggs. !65; Closes #19.


  • Support generic zip files (not just wheels). Closes #59

  • Support zip files with multiple distributions in them. Closes #60

  • Fully expose the public API in importlib_metadata.__all__.


  • The Distribution ABC is now officially part of the public API. Closes #37.

  • Fixed support for older single file egg-info formats. Closes #43.

  • Fixed a testing bug when $CWD has spaces in the path. Closes #50.

  • Add Python 3.8 to the tox testing matrix.


  • Fixed issue where entry points without an attribute would raise an Exception. Closes #40.

  • Removed unused name parameter from entry_points(). Closes #44.

  • DistributionFinder classes must now be instantiated before being placed on sys.meta_path.


  • This library can now discover/enumerate all installed packages. This backward-incompatible change alters the protocol finders must implement to support distribution package discovery. Closes #24.

  • The signature of find_distributions() on custom installer finders should now accept two parameters, name and path and these parameters must supply defaults.

  • The entry_points() method no longer accepts a package name but instead returns all entry points in a dictionary keyed by the EntryPoint.group. The resolve method has been removed. Instead, call EntryPoint.load(), which has the same semantics as pkg_resources and entrypoints. This is a backward incompatible change.

  • Metadata is now always returned as Unicode text regardless of Python version. Closes #29.

  • This library can now discover metadata for a ‘local’ package (found in the current-working directory). Closes #27.

  • Added files() function for resolving files from a distribution.

  • Added a new requires() function, which returns the requirements for a package suitable for parsing by packaging.requirements.Requirement. Closes #18.

  • The top-level read_text() function has been removed. Use PackagePath.read_text() on instances returned by the files() function. This is a backward incompatible change.

  • Release dates are now automatically injected into the changelog based on SCM tags.


  • Fixed issue where packages with dashes in their names would not be discovered. Closes #21.

  • Distribution lookup is now case-insensitive. Closes #20.

  • Wheel distributions can no longer be discovered by their module name. Like Path distributions, they must be indicated by their distribution package name.


  • Removed importlib_metadata.distribution function. Now the public interface is primarily the utility functions exposed in importlib_metadata.__all__. Closes #14.

  • Added two new utility functions read_text and metadata.


  • Updated README and removed details about Distribution class, now considered private. Closes #15.

  • Added test suite support for Python 3.4+.

  • Fixed SyntaxErrors on Python 3.4 and 3.5. !12

  • Fixed errors on Windows joining Path elements. !15


  • Housekeeping.


  • Added usage documentation. Closes #8

  • Add support for getting metadata from wheels on sys.path. Closes #9


  • Added importlib_metadata.entry_points(). Closes #1

  • Added importlib_metadata.resolve(). Closes #12

  • Add support for Python 2.7. Closes #4


  • Initial release.