Enable ruff's future-annotations and RUF* rules (#6245)

## Summary

This PR updates typing and linting across the codebase and enables
stricter `ruff` checks for Python 3.10:

1. Enable `tool.ruff.lint.future-annotations`
Very handy feature released in `0.13.0`: if required, it _automatically_
adds `from __future__ import annotations` and moves relevant imports
under `if TYPE_CHECKING`:

   ```py
   # before (runtime import)
   from beets.library import Library

   # after
   from __future__ import annotations

   from typing import TYPE_CHECKING

   if TYPE_CHECKING:
       from beets.library import Library
   ```

2. Set `tool.ruff.target-version = "py310"`

   This enforced PEP 604 unions in the codebase:

   ```py
   # before
   SQLiteType = Union[str, bytes, float, int, memoryview, None]

   # after
   SQLiteType = str | bytes | float | int | memoryview | None
   ```

3. Enable `RUF*` family of checks

   - Remove unused `# noqa`s
   - Ignore unused unpacked variables

     ```py
     # before
     likelies, consensus = util.get_most_common_tags(self.items)

     # after
     likelies, _ = util.get_most_common_tags(self.items)
     ```
   - Avoid list materialization
     ```py
     # before
     for part in parts + [","]:

     # after
     for part in [*parts, ","]:
     ```

- And, most importantly, **RUF012**: use `ClassVar` for mutable class
attributes

- This underlined our messy `BeetsPlugin.template_*` attributes design,
where I have now defined `BeetsPluginMeta` to make a clear distinction
between class and instance attributes. @semohr and @asardaes I saw you
had a discussion regarding these earlier - we will need to revisit this
at some point to sort it out for good.
- It also revealed a legitimate issue in `metasync.MetaSource` where
`item_types` were initialised as an instance attribute (but luckily
never used).

Author: snejus

.git-blame-ignore-revs

@@ -81,9 +81,17 @@ d93ddf8dd43e4f9ed072a03829e287c78d2570a2
 59c93e70139f70e9fd1c6f3c1bceb005945bec33
 # Moved ui.commands._utils into ui.commands.utils
 25ae330044abf04045e3f378f72bbaed739fb30d
-# Refactor test_ui_command.py into multiple modules 
+# Refactor test_ui_command.py into multiple modules
 a59e41a88365e414db3282658d2aa456e0b3468a
 # pyupgrade Python 3.10
 301637a1609831947cb5dd90270ed46c24b1ab1b
 # Fix changelog formatting
 658b184c59388635787b447983ecd3a575f4fe56
+# Configure future-annotations
+ac7f3d9da95c2d0a32e5c908ea68480518a1582d
+# Configure ruff for py310
+c46069654628040316dea9db85d01b263db3ba9e
+# Enable RUF rules
+4749599913a42e02e66b37db9190de11d6be2cdf
+# Address RUF012
+bc71ec308eb938df1d349f6857634ddf2a82e339

beets/autotag/match.py

@@ -25,14 +25,15 @@
 import numpy as np
 
 from beets import config, logging, metadata_plugins, plugins
-from beets.autotag import AlbumInfo, AlbumMatch, TrackInfo, TrackMatch, hooks
+from beets.autotag import AlbumMatch, TrackMatch, hooks
 from beets.util import get_most_common_tags
 
 from .distance import VA_ARTISTS, distance, track_distance
 
 if TYPE_CHECKING:
     from collections.abc import Iterable, Sequence
 
+    from beets.autotag import AlbumInfo, TrackInfo
     from beets.library import Item
 
 # Global logger.

beets/dbcore/db.py

@@ -26,17 +26,10 @@
 import time
 from abc import ABC
 from collections import defaultdict
-from collections.abc import (
-    Callable,
-    Generator,
-    Iterable,
-    Iterator,
-    Mapping,
-    Sequence,
-)
+from collections.abc import Mapping
 from functools import cached_property
-from sqlite3 import Connection, sqlite_version_info
-from typing import TYPE_CHECKING, Any, AnyStr, Generic
+from sqlite3 import sqlite_version_info
+from typing import TYPE_CHECKING, Any, AnyStr, ClassVar, Generic
 
 from typing_extensions import (
     Self,
@@ -48,20 +41,20 @@
 
 from ..util import cached_classproperty, functemplate
 from . import types
-from .query import (
-    FieldQueryType,
-    FieldSort,
-    MatchQuery,
-    NullSort,
-    Query,
-    Sort,
-    TrueQuery,
-)
+from .query import MatchQuery, NullSort, TrueQuery
 
 if TYPE_CHECKING:
+    from collections.abc import (
+        Callable,
+        Generator,
+        Iterable,
+        Iterator,
+        Sequence,
+    )
+    from sqlite3 import Connection
     from types import TracebackType
 
-    from .query import SQLiteType
+    from .query import FieldQueryType, FieldSort, Query, Sort, SQLiteType
 
 D = TypeVar("D", bound="Database", default=Any)
 
@@ -306,7 +299,7 @@ class Model(ABC, Generic[D]):
     """The flex field SQLite table name.
     """
 
-    _fields: dict[str, types.Type] = {}
+    _fields: ClassVar[dict[str, types.Type]] = {}
     """A mapping indicating available "fixed" fields on this type. The
     keys are field names and the values are `Type` objects.
     """
@@ -321,7 +314,7 @@ def _types(cls) -> dict[str, types.Type]:
         """Optional types for non-fixed (flexible and computed) fields."""
         return {}
 
-    _sorts: dict[str, type[FieldSort]] = {}
+    _sorts: ClassVar[dict[str, type[FieldSort]]] = {}
     """Optional named sort criteria. The keys are strings and the values
     are subclasses of `Sort`.
     """

beets/dbcore/query.py

@@ -20,17 +20,19 @@
 import re
 import unicodedata
 from abc import ABC, abstractmethod
-from collections.abc import Iterator, MutableSequence, Sequence
+from collections.abc import Sequence
 from datetime import datetime, timedelta
 from functools import cached_property, reduce
 from operator import mul, or_
 from re import Pattern
-from typing import TYPE_CHECKING, Any, Generic, TypeVar, Union
+from typing import TYPE_CHECKING, Any, ClassVar, Generic, TypeVar
 
 from beets import util
 from beets.util.units import raw_seconds_short
 
 if TYPE_CHECKING:
+    from collections.abc import Iterator, MutableSequence
+
     from beets.dbcore.db import AnyModel, Model
 
     P = TypeVar("P", default=Any)
@@ -122,7 +124,7 @@ def __hash__(self) -> int:
         return hash(type(self))
 
 
-SQLiteType = Union[str, bytes, float, int, memoryview, None]
+SQLiteType = str | bytes | float | int | memoryview | None
 AnySQLiteType = TypeVar("AnySQLiteType", bound=SQLiteType)
 FieldQueryType = type["FieldQuery"]
 
@@ -689,7 +691,12 @@ class Period:
         ("%Y-%m-%dT%H:%M", "%Y-%m-%d %H:%M"),  # minute
         ("%Y-%m-%dT%H:%M:%S", "%Y-%m-%d %H:%M:%S"),  # second
     )
-    relative_units = {"y": 365, "m": 30, "w": 7, "d": 1}
+    relative_units: ClassVar[dict[str, int]] = {
+        "y": 365,
+        "m": 30,
+        "w": 7,
+        "d": 1,
+    }
     relative_re = "(?P<sign>[+|-]?)(?P<quantity>[0-9]+)(?P<timespan>[y|m|w|d])"
 
     def __init__(self, date: datetime, precision: str):

beets/dbcore/queryparse.py

@@ -250,7 +250,7 @@ def parse_sorted_query(
     # Split up query in to comma-separated subqueries, each representing
     # an AndQuery, which need to be joined together in one OrQuery
     subquery_parts = []
-    for part in parts + [","]:
+    for part in [*parts, ","]:
         if part.endswith(","):
             # Ensure we can catch "foo, bar" as well as "foo , bar"
             last_subquery_part = part[:-1]

beets/dbcore/types.py

@@ -20,7 +20,7 @@
 import time
 import typing
 from abc import ABC
-from typing import TYPE_CHECKING, Any, Generic, TypeVar, cast
+from typing import TYPE_CHECKING, Any, ClassVar, Generic, TypeVar, cast
 
 import beets
 from beets import util
@@ -406,7 +406,7 @@ class MusicalKey(String):
     The standard format is C, Cm, C#, C#m, etc.
     """
 
-    ENHARMONIC = {
+    ENHARMONIC: ClassVar[dict[str, str]] = {
         r"db": "c#",
         r"eb": "d#",
         r"gb": "f#",

beets/importer/__init__.py

@@ -28,11 +28,11 @@
 # Note: Stages are not exposed to the public API
 
 __all__ = [
-    "ImportSession",
-    "ImportAbortError",
     "Action",
-    "ImportTask",
     "ArchiveImportTask",
+    "ImportAbortError",
+    "ImportSession",
+    "ImportTask",
     "SentinelImportTask",
     "SingletonImportTask",
 ]

beets/importer/session.py

@@ -17,7 +17,7 @@
 import time
 from typing import TYPE_CHECKING
 
-from beets import config, dbcore, library, logging, plugins, util
+from beets import config, logging, plugins, util
 from beets.importer.tasks import Action
 from beets.util import displayable_path, normpath, pipeline, syspath
 
@@ -27,6 +27,7 @@
 if TYPE_CHECKING:
     from collections.abc import Sequence
 
+    from beets import dbcore, library
     from beets.util import PathBytes
 
     from .tasks import ImportTask

beets/importer/stages.py

@@ -388,5 +388,5 @@ def _extend_pipeline(tasks, *stages):
     else:
         task_iter = tasks
 
-    ipl = pipeline.Pipeline([task_iter] + list(stages))
+    ipl = pipeline.Pipeline([task_iter, *list(stages)])
     return pipeline.multiple(ipl.pull())

beets/importer/tasks.py

@@ -20,7 +20,7 @@
 import shutil
 import time
 from collections import defaultdict
-from collections.abc import Callable, Iterable, Sequence
+from collections.abc import Callable
 from enum import Enum
 from tempfile import mkdtemp
 from typing import TYPE_CHECKING, Any
@@ -33,6 +33,8 @@
 from .state import ImportState
 
 if TYPE_CHECKING:
+    from collections.abc import Iterable, Sequence
+
     from beets.autotag.match import Recommendation
 
     from .session import ImportSession
@@ -232,7 +234,7 @@ def chosen_info(self):
         or APPLY (in which case the data comes from the choice).
         """
         if self.choice_flag in (Action.ASIS, Action.RETAG):
-            likelies, consensus = util.get_most_common_tags(self.items)
+            likelies, _ = util.get_most_common_tags(self.items)
             return likelies
         elif self.choice_flag is Action.APPLY and self.match:
             return self.match.info.copy()
@@ -890,7 +892,7 @@ def extract(self):
                 # The (0, 0, -1) is added to date_time because the
                 # function time.mktime expects a 9-element tuple.
                 # The -1 indicates that the DST flag is unknown.
-                date_time = time.mktime(f.date_time + (0, 0, -1))
+                date_time = time.mktime((*f.date_time, 0, 0, -1))
                 fullpath = os.path.join(extract_to, f.filename)
                 os.utime(fullpath, (date_time, date_time))