RFC: enable flake8-type-checking ruleset

pyproject.toml

@@ -295,6 +295,7 @@ select = [
     "C4",   # flake8-comprehensions
     "B",    # flake8-bugbear
     "G",    # flake8-logging-format
+    "TCH",  # flake8-type-checking
     "YTT",  # flake8-2020
     "UP",   # pyupgrade
     "I",    # isort

yt/data_objects/static_output.py

@@ -13,12 +13,11 @@
 from functools import cached_property
 from importlib.util import find_spec
 from stat import ST_CTIME
-from typing import Any, Literal, Optional, Union
+from typing import TYPE_CHECKING, Any, Literal, Optional, Union
 
 import numpy as np
 import unyt as un
 from more_itertools import unzip
-from sympy import Symbol
 from unyt import Unit, UnitSystem, unyt_quantity
 from unyt.exceptions import UnitConversionError, UnitParseError
 
@@ -74,6 +73,9 @@
 from yt.utilities.parallel_tools.parallel_analysis_interface import parallel_root_only
 from yt.utilities.parameter_file_storage import NoParameterShelf, ParameterFileStore
 
+if TYPE_CHECKING:
+    from sympy import Symbol
+
 if sys.version_info >= (3, 11):
     from typing import assert_never
 else:

yt/frontends/ramses/io.py

@@ -1,7 +1,6 @@
-import os
 from collections import defaultdict
 from functools import lru_cache
-from typing import Union
+from typing import TYPE_CHECKING, Union
 
 import numpy as np
 
@@ -17,6 +16,9 @@
 from yt.utilities.logger import ytLogger as mylog
 from yt.utilities.physical_ratios import cm_per_km, cm_per_mpc
 
+if TYPE_CHECKING:
+    import os
+
 
 def convert_ramses_ages(ds, conformal_ages):
     issue_deprecation_warning(

yt/visualization/fixed_resolution.py

@@ -30,7 +30,9 @@
     from typing_extensions import override
 
 if TYPE_CHECKING:
-    from yt.visualization.fixed_resolution_filters import FixedResolutionBufferFilter
+    from yt.visualization.fixed_resolution_filters import (
+        FixedResolutionBufferFilter,
+    )
 
 
 class FixedResolutionBuffer:
@@ -134,9 +136,6 @@ def __init__(
         # the filter methods for the present class are defined only when
         # fixed_resolution_filters is imported, so we need to guarantee
         # that it happens no later than instantiation
-        from yt.visualization.fixed_resolution_filters import (
-            FixedResolutionBufferFilter,
-        )
 
         self._filters: list[FixedResolutionBufferFilter] = (
             filters if filters is not None else []

yt/visualization/plot_window.py

@@ -2,7 +2,7 @@
 import sys
 from collections import defaultdict
 from numbers import Number
-from typing import Optional, Union
+from typing import TYPE_CHECKING, Optional, Union
 
 import matplotlib
 import numpy as np
@@ -55,6 +55,9 @@
     invalidate_plot,
 )
 
+if TYPE_CHECKING:
+    from yt.visualization.plot_modifications import PlotCallback
+
 if sys.version_info < (3, 10):
     from yt._maintenance.backports import zip
 
@@ -866,7 +869,6 @@ def __init__(self, *args, **kwargs) -> None:
         # the filter methods for the present class are defined only when
         # fixed_resolution_filters is imported, so we need to guarantee
         # that it happens no later than instantiation
-        from yt.visualization.plot_modifications import PlotCallback
 
         self._callbacks: list[PlotCallback] = []
 

yt/visualization/profile_plotter.py

@@ -1,15 +1,13 @@
 import base64
 import builtins
 import os
-from collections.abc import Iterable
 from functools import wraps
-from typing import Any, Optional, Union
+from typing import TYPE_CHECKING, Any, Optional, Union
 
 import matplotlib
 import numpy as np
 from more_itertools.more import always_iterable, unzip
 
-from yt._typing import FieldKey
 from yt.data_objects.profiles import create_profile, sanitize_field_tuple_keys
 from yt.data_objects.static_output import Dataset
 from yt.frontends.ytdata.data_structures import YTProfileDataset
@@ -28,6 +26,11 @@
     validate_plot,
 )
 
+if TYPE_CHECKING:
+    from collections.abc import Iterable
+
+    from yt._typing import FieldKey
+
 
 def invalidate_profile(f):
     @wraps(f)