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From a65c29adc027b3615154cab73aaedd58a6aa23da Mon Sep 17 00:00:00 2001
From: "Jason R. Coombs" <jaraco@jaraco.com>
Date: Tue, 23 Jul 2024 08:36:16 -0400
Subject: [PATCH] Prioritize valid dists to invalid dists when retrieving by
name.
Closes python/importlib_metadata#489
Upstream-Status: Backport [https://github.com/python/importlib_metadata/commit/a65c29adc027b3615154cab73aaedd58a6aa23da]
Signed-off-by: Ross Burton <ross.burton@arm.com>
diff --git i/Lib/importlib/metadata/__init__.py w/Lib/importlib/metadata/__init__.py
index 8ce62dd864f..085378caabc 100644
--- i/Lib/importlib/metadata/__init__.py
+++ w/Lib/importlib/metadata/__init__.py
@@ -21,7 +21,7 @@
from . import _meta
from ._collections import FreezableDefaultDict, Pair
from ._functools import method_cache, pass_none
-from ._itertools import always_iterable, unique_everseen
+from ._itertools import always_iterable, bucket, unique_everseen
from ._meta import PackageMetadata, SimplePath
from contextlib import suppress
@@ -404,7 +404,7 @@ def from_name(cls, name: str) -> Distribution:
if not name:
raise ValueError("A distribution name is required.")
try:
- return next(iter(cls.discover(name=name)))
+ return next(iter(cls._prefer_valid(cls.discover(name=name))))
except StopIteration:
raise PackageNotFoundError(name)
@@ -428,6 +428,16 @@ def discover(
resolver(context) for resolver in cls._discover_resolvers()
)
+ @staticmethod
+ def _prefer_valid(dists: Iterable[Distribution]) -> Iterable[Distribution]:
+ """
+ Prefer (move to the front) distributions that have metadata.
+
+ Ref python/importlib_resources#489.
+ """
+ buckets = bucket(dists, lambda dist: bool(dist.metadata))
+ return itertools.chain(buckets[True], buckets[False])
+
@staticmethod
def at(path: str | os.PathLike[str]) -> Distribution:
"""Return a Distribution for the indicated metadata path.
diff --git i/Lib/importlib/metadata/_itertools.py w/Lib/importlib/metadata/_itertools.py
index d4ca9b9140e..79d37198ce7 100644
--- i/Lib/importlib/metadata/_itertools.py
+++ w/Lib/importlib/metadata/_itertools.py
@@ -1,3 +1,4 @@
+from collections import defaultdict, deque
from itertools import filterfalse
@@ -71,3 +72,100 @@ def always_iterable(obj, base_type=(str, bytes)):
return iter(obj)
except TypeError:
return iter((obj,))
+
+
+# Copied from more_itertools 10.3
+class bucket:
+ """Wrap *iterable* and return an object that buckets the iterable into
+ child iterables based on a *key* function.
+
+ >>> iterable = ['a1', 'b1', 'c1', 'a2', 'b2', 'c2', 'b3']
+ >>> s = bucket(iterable, key=lambda x: x[0]) # Bucket by 1st character
+ >>> sorted(list(s)) # Get the keys
+ ['a', 'b', 'c']
+ >>> a_iterable = s['a']
+ >>> next(a_iterable)
+ 'a1'
+ >>> next(a_iterable)
+ 'a2'
+ >>> list(s['b'])
+ ['b1', 'b2', 'b3']
+
+ The original iterable will be advanced and its items will be cached until
+ they are used by the child iterables. This may require significant storage.
+
+ By default, attempting to select a bucket to which no items belong will
+ exhaust the iterable and cache all values.
+ If you specify a *validator* function, selected buckets will instead be
+ checked against it.
+
+ >>> from itertools import count
+ >>> it = count(1, 2) # Infinite sequence of odd numbers
+ >>> key = lambda x: x % 10 # Bucket by last digit
+ >>> validator = lambda x: x in {1, 3, 5, 7, 9} # Odd digits only
+ >>> s = bucket(it, key=key, validator=validator)
+ >>> 2 in s
+ False
+ >>> list(s[2])
+ []
+
+ """
+
+ def __init__(self, iterable, key, validator=None):
+ self._it = iter(iterable)
+ self._key = key
+ self._cache = defaultdict(deque)
+ self._validator = validator or (lambda x: True)
+
+ def __contains__(self, value):
+ if not self._validator(value):
+ return False
+
+ try:
+ item = next(self[value])
+ except StopIteration:
+ return False
+ else:
+ self._cache[value].appendleft(item)
+
+ return True
+
+ def _get_values(self, value):
+ """
+ Helper to yield items from the parent iterator that match *value*.
+ Items that don't match are stored in the local cache as they
+ are encountered.
+ """
+ while True:
+ # If we've cached some items that match the target value, emit
+ # the first one and evict it from the cache.
+ if self._cache[value]:
+ yield self._cache[value].popleft()
+ # Otherwise we need to advance the parent iterator to search for
+ # a matching item, caching the rest.
+ else:
+ while True:
+ try:
+ item = next(self._it)
+ except StopIteration:
+ return
+ item_value = self._key(item)
+ if item_value == value:
+ yield item
+ break
+ elif self._validator(item_value):
+ self._cache[item_value].append(item)
+
+ def __iter__(self):
+ for item in self._it:
+ item_value = self._key(item)
+ if self._validator(item_value):
+ self._cache[item_value].append(item)
+
+ yield from self._cache.keys()
+
+ def __getitem__(self, value):
+ if not self._validator(value):
+ return iter(())
+
+ return self._get_values(value)
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