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PyPI · #988 most downloaded on PyPI
Resolve abstract dependencies into concrete ones
Last release 11 months ago
11 Oct 2025
Release timing varies
gaps range from 8 days to 1.6 years
Nearly every release is documented
notes for 20 of 21 stable releases
1 version withdrawn
withdrawn after publishing
8 years old
23 releases · first in 2018
Add extra guard to prevent the states from being exhausted during backjumping. #195 _
One column per quarter.
No significant changes.
No significant changes.
Declare supported Python version support ">= 3.7" in dist meta #129 _
Declare supported Python version support ">= 3.7" in dist meta #129
Improve exception chaining when ResolutionImpossible raises during backjumping #133
Switch from pyi files to modern annotations based type hinting #135
In tests the commentjson test dependency with re.sub #141
Deduplicate failure causes to save memory and reduce backtracking overhead #143
New narrow_requirement_selection provider method giving option for providers to reduce the number of times sort key get_preference is called in long running backtrack #145
Run tests against Python 3.12, 3.13, and use latest version of CI dependencies #153
Update py2ndex script to use metadata files, skip 404, and support PEP 723 #156
Replace setuptools.cfg and mypy.ini with pyproject.toml #157
Add tests type "unvisited" to functional Python tests to ensure backjumping is correctly skipping candidates #158
Switch from flake8 to ruff for linting #160
Enable automatic TYPE_CHECK guarding for imports only used for type hinting via ruff rules TCH and FA #166
Fix example reporter_demo get_preference method which requires arg backtrack_causes #136
Clarify the docstrings for providers.py #138
Pin Black version for linting to prevent CI failures #150
In unexpected situation where broken_state.mapping is empty, stop backtracking, and continue resolution (rather than throwing ResolutionImpossible) #152
During backtracking check if the current broken state is an incompatible dependency, if not stop backtracking and continue resolution. #155
Separate AbstractResolver and Resolver into different modules #162
Separate resolvers into different modules #163
Export criterion in resolvers to keep compatibility #164
Enable isorting via ruff #165
Fix calls to opaque objects and use provider interface calls instead. #126 _
Fix calls to opaque objects and use provider interface calls instead. #126
Implement backjumping to significantly speed up the resolution process by skipping over irrelevant parts of the resolution search space. #113 _
Implement backjumping to significantly speed up the resolution process by skipping over irrelevant parts of the resolution search space. #113
A new reporter hook rejecting_candidate is added, replacing backtracking. The hook is called every time the resolver rejects a conflicting candidate b
A new reporter hook rejecting_candidate is added, replacing backtracking. The hook is called every time the resolver rejects a conflicting candidate before trying out the next one in line. #101
Some valid states that were previously rejected are now accepted. This affects states where multiple candidates for the same dependency conflict with each other. The information argument passed to AbstractProvider.get_preference may now contain empty iterators. This has always been allowed by the method definition but it was previously not possible in practice. #91
A new reporter hook resolving_conflicts is added. The resolver triggers this hook when it detects conflicts in the dependency tree, and before it atte
A new reporter hook resolving_conflicts is added. The resolver triggers this hook when it detects conflicts in the dependency tree, and before it attempts to fix them. The hook accepts one single argument causes, which is a list of (requirement, parent) 2-tuples that represents all the edges that lead to the detected conflicts. #81
Add backtrack_causes to get_preference, which contains information about the requirements involved in the most recent backtrack. This allows the provi
Add backtrack_causes to get_preference, which contains information about the requirements involved in the most recent backtrack. This allows the provider to utilise this information to tweak the ordering as well as for recording/reporting conflicts.
When merging a candidate's dependencies, make sure the merge target is up-to-date within the loop, so the merge does not lose information when a candi
When merging a candidate's dependencies, make sure the merge target is up-to-date within the loop, so the merge does not lose information when a candidate returns multiple dependency specifications under one identifier (e.g. specifyiung two dependencies a>1 and a<2, instead of one single a>1,<2 dependency). #80
Redesign get_preference() to include resolution state on dependencies other than the currently working one, to allow the provider to better take accou
Redesign get_preference() to include resolution state on dependencies other than the currently working one, to allow the provider to better take account of the global resolver knowledge and determine the best strategy. The provider now can, for example, correctly calculate how far a dependency is from the root node in the graph. #74
A new argument incompatibilities is now passed to the find_matches() hook, which the provider must use to exclude matches from the return value. #68 _
A new argument incompatibilities is now passed to the find_matches() hook, which the provider must use to exclude matches from the return value. #68
Redesign find_matches() to include resolution state on dependencies other than the currently working one, to handle usages that need to return candidates based on non-local states. One such example is PEP 508 direct URLs specified on a package, which need to be available to the same package specified with extras (which would have a different identifier). #74
The resolver no longer relies on implicit candidate equality to detect incompatibilities. This is done by an additional find_matches() argument; see the Features section to learn more. #68
Provide type stubs for most classes. #72 _
Provide type stubs for most classes. #72
No significant changes.
No significant changes.
Fix a state management bug that causes the resolver to enter an infinite loop in certain backtracking cases. #62 _
Fix a state management bug that causes the resolver to enter an infinite loop in certain backtracking cases. #62
Fix a performance regression if find_matches() returns a non-built-in sequence instance.
Fix a performance regression if find_matches() returns a non-built-in sequence instance.
find_matches() now may return a Callable[[], Iterator[Candidate]] to avoid needing to provide all candidates eagerly for the resolver. This improves p
find_matches() now may return a Callable[[], Iterator[Candidate]] to avoid needing to provide all candidates eagerly for the resolver. This improves performance when fetching candidates is costly, but not always required. #57
Add parent argument to the add_requirement() reporter hook. #46 _
Provide both the requirements and their parents as exceptiondata for the ResolutionImpossible exception, via a causes attribute that replaces the prev
Provide both the requirements and their parents as exceptiondata for the ResolutionImpossible exception, via a causes attribute that replaces the previous requirements attribute. #42
Make resolver backtrack when none of the candidates requested for a package are able to resolve due to them requesting unworkable requirements, or a package has no candidates at all. Previously the resolver would give up on the spot. #18
Ensure the result returned by the resolver only contains candidates that are actually needed. This is done by tracing the graph after resolution completes, snipping nodes that don’t have a route to the root. #4
Remove reporting callbacks adding_requirements, adding_candidate, and replacing_candidate added in 0.2.1. These are not useful, and it’s better to rem
Remove reporting callbacks adding_requirements, adding_candidate, and replacing_candidate added in 0.2.1. These are not useful, and it’s better to remove them while we can. #6
Add new reporting callbacks adding_requirements, adding_candidate, and replacing_candidate to report progress in requirement pinning. #2 _
Resolver.resolve() now returns a namedtuple with public attributes, instead of an internal Resolution object.
Resolver.resolve() now returns a namedtuple with public attributes, instead of an internal Resolution object.
Update trove classifiers on PyPI to better reflect the project's intentions.
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