remove default parameters for parametric dtypes; add mixin classes for numpy dtypes; define zdtypelike

Author: d-v-b

src/zarr/api/synchronous.py

@@ -37,6 +37,7 @@
         ShapeLike,
         ZarrFormat,
     )
+    from zarr.core.dtype import ZDTypeLike
     from zarr.storage import StoreLike
 
 __all__ = [
@@ -748,7 +749,7 @@ def create_array(
     *,
     name: str | None = None,
     shape: ShapeLike | None = None,
-    dtype: npt.DTypeLike | None = None,
+    dtype: ZDTypeLike | None = None,
     data: np.ndarray[Any, np.dtype[Any]] | None = None,
     chunks: ChunkCoords | Literal["auto"] = "auto",
     shards: ShardsLike | None = None,
@@ -778,7 +779,7 @@ def create_array(
         at the root of the store.
     shape : ChunkCoords, optional
         Shape of the array. Can be ``None`` if ``data`` is provided.
-    dtype : npt.DTypeLike, optional
+    dtype : ZDTypeLike, optional
         Data type of the array. Can be ``None`` if ``data`` is provided.
     data : np.ndarray, optional
         Array-like data to use for initializing the array. If this parameter is provided, the

src/zarr/core/array.py

@@ -23,7 +23,6 @@
 import numcodecs
 import numcodecs.abc
 import numpy as np
-import numpy.typing as npt
 from typing_extensions import deprecated
 
 from zarr._compat import _deprecate_positional_args
@@ -67,6 +66,7 @@
 from zarr.core.config import config as zarr_config
 from zarr.core.dtype import (
     ZDType,
+    ZDTypeLike,
     parse_data_type,
 )
 from zarr.core.indexing import (
@@ -122,6 +122,8 @@
     from collections.abc import Iterator, Sequence
     from typing import Self
 
+    import numpy.typing as npt
+
     from zarr.abc.codec import CodecPipeline
     from zarr.codecs.sharding import ShardingCodecIndexLocation
     from zarr.core.dtype.wrapper import _BaseDType, _BaseScalar
@@ -295,7 +297,7 @@ async def create(
         *,
         # v2 and v3
         shape: ShapeLike,
-        dtype: npt.DTypeLike,
+        dtype: ZDTypeLike,
         zarr_format: Literal[2],
         fill_value: Any | None = None,
         attributes: dict[str, JSON] | None = None,
@@ -319,7 +321,7 @@ async def create(
         *,
         # v2 and v3
         shape: ShapeLike,
-        dtype: npt.DTypeLike,
+        dtype: ZDTypeLike,
         zarr_format: Literal[3],
         fill_value: Any | None = None,
         attributes: dict[str, JSON] | None = None,
@@ -347,7 +349,7 @@ async def create(
         *,
         # v2 and v3
         shape: ShapeLike,
-        dtype: npt.DTypeLike,
+        dtype: ZDTypeLike,
         zarr_format: Literal[3] = 3,
         fill_value: Any | None = None,
         attributes: dict[str, JSON] | None = None,
@@ -375,7 +377,7 @@ async def create(
         *,
         # v2 and v3
         shape: ShapeLike,
-        dtype: npt.DTypeLike,
+        dtype: ZDTypeLike,
         zarr_format: ZarrFormat,
         fill_value: Any | None = None,
         attributes: dict[str, JSON] | None = None,
@@ -410,7 +412,7 @@ async def create(
         *,
         # v2 and v3
         shape: ShapeLike,
-        dtype: npt.DTypeLike,
+        dtype: ZDTypeLike,
         zarr_format: ZarrFormat = 3,
         fill_value: Any | None = None,
         attributes: dict[str, JSON] | None = None,
@@ -446,7 +448,7 @@ async def create(
             The store where the array will be created.
         shape : ShapeLike
             The shape of the array.
-        dtype : npt.DTypeLike
+        dtype : ZDTypeLike
             The data type of the array.
         zarr_format : ZarrFormat, optional
             The Zarr format version (default is 3).
@@ -551,7 +553,7 @@ async def _create(
         *,
         # v2 and v3
         shape: ShapeLike,
-        dtype: npt.DTypeLike | ZDType[_BaseDType, _BaseScalar],
+        dtype: ZDTypeLike | ZDType[_BaseDType, _BaseScalar],
         zarr_format: ZarrFormat = 3,
         fill_value: Any | None = None,
         attributes: dict[str, JSON] | None = None,
@@ -1746,7 +1748,7 @@ def create(
         *,
         # v2 and v3
         shape: ChunkCoords,
-        dtype: npt.DTypeLike,
+        dtype: ZDTypeLike,
         zarr_format: ZarrFormat = 3,
         fill_value: Any | None = None,
         attributes: dict[str, JSON] | None = None,
@@ -1781,7 +1783,7 @@ def create(
             The array store that has already been initialized.
         shape : ChunkCoords
             The shape of the array.
-        dtype : npt.DTypeLike
+        dtype : ZDTypeLike
             The data type of the array.
         chunk_shape : ChunkCoords, optional
             The shape of the Array's chunks.
@@ -1875,7 +1877,7 @@ def _create(
         *,
         # v2 and v3
         shape: ChunkCoords,
-        dtype: npt.DTypeLike,
+        dtype: ZDTypeLike,
         zarr_format: ZarrFormat = 3,
         fill_value: Any | None = None,
         attributes: dict[str, JSON] | None = None,
@@ -3817,7 +3819,7 @@ async def init_array(
     *,
     store_path: StorePath,
     shape: ShapeLike,
-    dtype: npt.DTypeLike,
+    dtype: ZDTypeLike,
     chunks: ChunkCoords | Literal["auto"] = "auto",
     shards: ShardsLike | None = None,
     filters: FiltersLike = "auto",
@@ -3840,7 +3842,7 @@ async def init_array(
         StorePath instance. The path attribute is the name of the array to initialize.
     shape : ChunkCoords
         Shape of the array.
-    dtype : npt.DTypeLike
+    dtype : ZDTypeLike
         Data type of the array.
     chunks : ChunkCoords, optional
         Chunk shape of the array.
@@ -4028,7 +4030,7 @@ async def create_array(
     *,
     name: str | None = None,
     shape: ShapeLike | None = None,
-    dtype: npt.DTypeLike | None = None,
+    dtype: ZDTypeLike | None = None,
     data: np.ndarray[Any, np.dtype[Any]] | None = None,
     chunks: ChunkCoords | Literal["auto"] = "auto",
     shards: ShardsLike | None = None,
@@ -4057,7 +4059,7 @@ async def create_array(
         at the root of the store.
     shape : ChunkCoords, optional
         Shape of the array. Can be ``None`` if ``data`` is provided.
-    dtype : npt.DTypeLike | None
+    dtype : ZDTypeLike | None
         Data type of the array. Can be ``None`` if ``data`` is provided.
     data : Array-like data to use for initializing the array. If this parameter is provided, the
         ``shape`` and ``dtype`` parameters must be identical to ``data.shape`` and ``data.dtype``,
@@ -4401,8 +4403,8 @@ def _parse_data_params(
     *,
     data: np.ndarray[Any, np.dtype[Any]] | None,
     shape: ShapeLike | None,
-    dtype: npt.DTypeLike | None,
-) -> tuple[np.ndarray[Any, np.dtype[Any]] | None, ShapeLike, npt.DTypeLike]:
+    dtype: ZDTypeLike | None,
+) -> tuple[np.ndarray[Any, np.dtype[Any]] | None, ShapeLike, ZDTypeLike]:
     """
     Ensure an array-like ``data`` parameter is consistent with the ``dtype`` and ``shape``
     parameters.

src/zarr/core/dtype/__init__.py

@@ -1,19 +1,16 @@
 from __future__ import annotations
 
-from typing import TYPE_CHECKING, Any, get_args
-
-import numpy as np
-
-from zarr.core.dtype._numpy import _NUMPY_SUPPORTS_VLEN_STRING
-from zarr.core.dtype.wrapper import _BaseDType, _BaseScalar
+from typing import TYPE_CHECKING, Any, TypeAlias, get_args
 
 if TYPE_CHECKING:
-    import numpy.typing as npt
-
-    from zarr.core.common import JSON, ZarrFormat
+    from zarr.core.common import ZarrFormat
 
+import numpy as np
+import numpy.typing as npt
 
+from zarr.core.common import JSON
 from zarr.core.dtype._numpy import (
+    _NUMPY_SUPPORTS_VLEN_STRING,
     Bool,
     Complex64,
     Complex128,
@@ -36,7 +33,7 @@
     VariableLengthString,
 )
 from zarr.core.dtype.registry import DataTypeRegistry
-from zarr.core.dtype.wrapper import ZDType
+from zarr.core.dtype.wrapper import ZDType, _BaseDType, _BaseScalar
 
 __all__ = [
     "Complex64",
@@ -80,6 +77,8 @@
     | DateTime64
 )
 
+ZDTypeLike: TypeAlias = npt.DTypeLike | ZDType[Any, Any] | dict[str, JSON]
+
 for dtype in get_args(DTYPE):
     data_type_registry.register(dtype._zarr_v3_name, dtype)
 
@@ -112,9 +111,10 @@ def get_data_type_from_json(
     return data_type_registry.match_json(dtype, zarr_format=zarr_format)
 
 
-def parse_data_type(
-    dtype: npt.DTypeLike | ZDType[Any, Any] | dict[str, JSON], zarr_format: ZarrFormat
-) -> ZDType[Any, Any]:
+def parse_data_type(dtype: ZDTypeLike, zarr_format: ZarrFormat) -> ZDType[Any, Any]:
+    """
+    Interpret the input as a ZDType instance.
+    """
     if isinstance(dtype, ZDType):
         return dtype
     elif isinstance(dtype, dict):