Resolve some 'mypy' errors (#5282)

## Description

I noticed that some development work was waiting on cleaner `mypy` runs,
so I thought I would help out a bit. This PR just contains a number of
miscellaneous fixes across the codebase that I hit. I'm happy to add
more, or remove any problematic changes (though I don't think I've
broken anything, only type annotations have changed).

## To Do

- [x] ~Documentation~
- [ ] Changelog
- [x] ~Tests~

beets/autotag/hooks.py

@@ -28,6 +28,7 @@ from typing import (
     List,
     Optional,
     Tuple,
+    TypeVar,
     Union,
     cast,
 )
@@ -42,20 +43,22 @@ from beets.util import as_string
 
 log = logging.getLogger("beets")
 
+V = TypeVar("V")
+
 
 # Classes used to represent candidate options.
-class AttrDict(dict):
+class AttrDict(Dict[str, V]):
     """A dictionary that supports attribute ("dot") access, so `d.field`
     is equivalent to `d['field']`.
     """
 
-    def __getattr__(self, attr):
+    def __getattr__(self, attr: str) -> V:
         if attr in self:
-            return self.get(attr)
+            return self[attr]
         else:
             raise AttributeError
 
-    def __setattr__(self, key, value):
+    def __setattr__(self, key: str, value: V):
         self.__setitem__(key, value)
 
     def __hash__(self):
@@ -79,7 +82,7 @@ class AlbumInfo(AttrDict):
     # TYPING: are all of these correct? I've assumed optional strings
     def __init__(
         self,
-        tracks: List["TrackInfo"],
+        tracks: List[TrackInfo],
         album: Optional[str] = None,
         album_id: Optional[str] = None,
         artist: Optional[str] = None,
@@ -201,7 +204,7 @@ class AlbumInfo(AttrDict):
         for track in self.tracks:
             track.decode(codec)
 
-    def copy(self) -> "AlbumInfo":
+    def copy(self) -> AlbumInfo:
         dupe = AlbumInfo([])
         dupe.update(self)
         dupe.tracks = [track.copy() for track in self.tracks]
@@ -309,7 +312,7 @@ class TrackInfo(AttrDict):
             if isinstance(value, bytes):
                 setattr(self, fld, value.decode(codec, "ignore"))
 
-    def copy(self) -> "TrackInfo":
+    def copy(self) -> TrackInfo:
         dupe = TrackInfo()
         dupe.update(self)
         return dupe
@@ -545,7 +548,7 @@ class Distance:
 
     # Adding components.
 
-    def _eq(self, value1: Union[re.Pattern, Any], value2: Any) -> bool:
+    def _eq(self, value1: Union[re.Pattern[str], Any], value2: Any) -> bool:
         """Returns True if `value1` is equal to `value2`. `value1` may
         be a compiled regular expression, in which case it will be
         matched against `value2`.

beets/autotag/match.py

@@ -238,7 +238,7 @@ def distance(
     if album_info.media:
         # Preferred media options.
         patterns = config["match"]["preferred"]["media"].as_str_seq()
-        patterns = cast(Sequence, patterns)
+        patterns = cast(Sequence[str], patterns)
         options = [re.compile(r"(\d+x)?(%s)" % pat, re.I) for pat in patterns]
         if options:
             dist.add_priority("media", album_info.media, options)
@@ -276,7 +276,7 @@ def distance(
 
     # Preferred countries.
     patterns = config["match"]["preferred"]["countries"].as_str_seq()
-    patterns = cast(Sequence, patterns)
+    patterns = cast(Sequence[str], patterns)
     options = [re.compile(pat, re.I) for pat in patterns]
     if album_info.country and options:
         dist.add_priority("country", album_info.country, options)
@@ -440,7 +440,9 @@ def _add_candidate(
         return
 
     # Discard matches without required tags.
-    for req_tag in cast(Sequence, config["match"]["required"].as_str_seq()):
+    for req_tag in cast(
+        Sequence[str], config["match"]["required"].as_str_seq()
+    ):
         if getattr(info, req_tag) is None:
             log.debug("Ignored. Missing required tag: {0}", req_tag)
             return
@@ -469,7 +471,7 @@ def tag_album(
     items,
     search_artist: Optional[str] = None,
     search_album: Optional[str] = None,
-    search_ids: List = [],
+    search_ids: List[str] = [],
 ) -> Tuple[str, str, Proposal]:
     """Return a tuple of the current artist name, the current album
     name, and a `Proposal` containing `AlbumMatch` candidates.
@@ -561,7 +563,7 @@ def tag_item(
     item,
     search_artist: Optional[str] = None,
     search_title: Optional[str] = None,
-    search_ids: List = [],
+    search_ids: Optional[List[str]] = None,
 ) -> Proposal:
     """Find metadata for a single track. Return a `Proposal` consisting
     of `TrackMatch` objects.

beets/dbcore/db.py

@@ -58,7 +58,6 @@ from . import types
 from .query import (
     AndQuery,
     FieldQuery,
-    FieldSort,
     MatchQuery,
     NullSort,
     Query,
@@ -303,7 +302,7 @@ class Model(ABC):
     """Optional Types for non-fixed (i.e., flexible and computed) fields.
     """
 
-    _sorts: Dict[str, Type[FieldSort]] = {}
+    _sorts: Dict[str, Type[Sort]] = {}
     """Optional named sort criteria. The keys are strings and the values
     are subclasses of `Sort`.
     """

beets/dbcore/query.py

@@ -256,7 +256,7 @@ class SubstringQuery(StringFieldQuery[str]):
         return pattern.lower() in value.lower()
 
 
-class RegexpQuery(StringFieldQuery[Pattern]):
+class RegexpQuery(StringFieldQuery[Pattern[str]]):
     """A query that matches a regular expression in a specific Model field.
 
     Raises InvalidQueryError when the pattern is not a valid regular
@@ -342,7 +342,7 @@ class BytesQuery(FieldQuery[bytes]):
         return pattern == value
 
 
-class NumericQuery(FieldQuery):
+class NumericQuery(FieldQuery[str]):
     """Matches numeric fields. A syntax using Ruby-style range ellipses
     (``..``) lets users specify one- or two-sided ranges. For example,
     ``year:2001..`` finds music released since the turn of the century.
@@ -787,7 +787,7 @@ class DateInterval:
         return f"[{self.start}, {self.end})"
 
 
-class DateQuery(FieldQuery):
+class DateQuery(FieldQuery[str]):
     """Matches date fields stored as seconds since Unix epoch time.
 
     Dates can be specified as ``year-month-day`` strings where only year
@@ -797,7 +797,7 @@ class DateQuery(FieldQuery):
     using an ellipsis interval syntax similar to that of NumericQuery.
     """
 
-    def __init__(self, field, pattern, fast: bool = True):
+    def __init__(self, field: str, pattern: str, fast: bool = True):
         super().__init__(field, pattern, fast)
         start, end = _parse_periods(pattern)
         self.interval = DateInterval.from_periods(start, end)

beets/dbcore/types.py

@@ -232,7 +232,7 @@ class BaseFloat(Type[float, N]):
     """
 
     sql = "REAL"
-    query = NumericQuery
+    query: typing.Type[FieldQuery[Any]] = NumericQuery
     model_type = float
 
     def __init__(self, digits: int = 1):

beets/library.py

@@ -49,7 +49,7 @@ log = logging.getLogger("beets")
 # Library-specific query types.
 
 
-class SingletonQuery(dbcore.FieldQuery):
+class SingletonQuery(dbcore.FieldQuery[str]):
     """This query is responsible for the 'singleton' lookup.
 
     It is based on the FieldQuery and constructs a SQL clause
@@ -60,14 +60,14 @@ class SingletonQuery(dbcore.FieldQuery):
     and singleton:false, singleton:0 are handled consistently.
     """
 
-    def __new__(cls, field, value, *args, **kwargs):
+    def __new__(cls, field: str, value: str, *args, **kwargs):
         query = dbcore.query.NoneQuery("album_id")
         if util.str2bool(value):
             return query
         return dbcore.query.NotQuery(query)
 
 
-class PathQuery(dbcore.FieldQuery):
+class PathQuery(dbcore.FieldQuery[bytes]):
     """A query that matches all items under a given path.
 
     Matching can either be case-insensitive or case-sensitive. By
@@ -185,7 +185,7 @@ class DateType(types.Float):
                 return self.null
 
 
-class PathType(types.Type):
+class PathType(types.Type[bytes, bytes]):
     """A dbcore type for filesystem paths.
 
     These are represented as `bytes` objects, in keeping with
@@ -384,7 +384,7 @@ class LibModel(dbcore.Model):
     """Shared concrete functionality for Items and Albums."""
 
     # Config key that specifies how an instance should be formatted.
-    _format_config_key = None
+    _format_config_key: str
 
     def _template_funcs(self):
         funcs = DefaultTemplateFunctions(self, self._db).functions()

beetsplug/bareasc.py

@@ -27,7 +27,7 @@ from beets.plugins import BeetsPlugin
 from beets.ui import decargs, print_
 
 
-class BareascQuery(StringFieldQuery):
+class BareascQuery(StringFieldQuery[str]):
     """Compare items using bare ASCII, without accents etc."""
 
     @classmethod

beetsplug/bpd/__init__.py

@@ -27,6 +27,7 @@ import sys
 import time
 import traceback
 from string import Template
+from typing import List
 
 from mediafile import MediaFile
 
@@ -1059,7 +1060,7 @@ class Command:
             raise BPDError(ERROR_SYSTEM, "server error", self.name)
 
 
-class CommandList(list):
+class CommandList(List[Command]):
     """A list of commands issued by the client for processing by the
     server. May be verbose, in which case the response is delimited, or
     not. Should be a list of `Command` objects.

beetsplug/fuzzy.py

@@ -23,9 +23,9 @@ from beets.dbcore.query import StringFieldQuery
 from beets.plugins import BeetsPlugin
 
 
-class FuzzyQuery(StringFieldQuery):
+class FuzzyQuery(StringFieldQuery[str]):
     @classmethod
-    def string_match(cls, pattern, val):
+    def string_match(cls, pattern: str, val: str):
         # smartcase
         if pattern.islower():
             val = val.lower()

beetsplug/replaygain.py

@@ -1440,7 +1440,7 @@ class ReplayGainPlugin(BeetsPlugin):
         """Open a `ThreadPool` instance in `self.pool`"""
         if self.pool is None and self.backend_instance.do_parallel:
             self.pool = ThreadPool(threads)
-            self.exc_queue: queue.Queue[Exception] = queue.Queue()
+            self.exc_queue: queue.Queue = queue.Queue()
 
             signal.signal(signal.SIGINT, self._interrupt)
 

beetsplug/the.py

@@ -16,6 +16,7 @@
 
 
 import re
+from typing import List
 
 from beets.plugins import BeetsPlugin
 
@@ -28,7 +29,7 @@ FORMAT = "{0}, {1}"
 
 
 class ThePlugin(BeetsPlugin):
-    patterns = []
+    patterns: List[str] = []
 
     def __init__(self):
         super().__init__()

test/plugins/test_albumtypes.py

@@ -16,6 +16,7 @@
 
 
 import unittest
+from typing import Sequence, Tuple
 
 from beets.autotag.mb import VARIOUS_ARTISTS_ID
 from beets.test.helper import TestHelper
@@ -98,12 +99,17 @@ class AlbumTypesPluginTest(unittest.TestCase, TestHelper):
         result = subject._atypes(album)
         self.assertEqual("[EP][Single][OST][Live][Remix]", result)
 
-    def _set_config(self, types: [(str, str)], ignore_va: [str], bracket: str):
+    def _set_config(
+        self,
+        types: Sequence[Tuple[str, str]],
+        ignore_va: Sequence[str],
+        bracket: str,
+    ):
         self.config["albumtypes"]["types"] = types
         self.config["albumtypes"]["ignore_va"] = ignore_va
         self.config["albumtypes"]["bracket"] = bracket
 
-    def _create_album(self, album_types: [str], artist_id: str = 0):
+    def _create_album(self, album_types: Sequence[str], artist_id: str = "0"):
         return self.add_album(
             albumtypes=album_types, mb_albumartistid=artist_id
         )