issue zarr-developers#3795: Create public types for metadata objects

Expose metadata types as public API from the main zarr module:
- ArrayV2Metadata and ArrayV3Metadata from zarr.core.metadata
- GroupMetadata, ImplicitGroupMarker, and ConsolidatedMetadata from zarr.core.group
- ChunkGrid and RegularChunkGrid from zarr.core.chunk_grids
- ChunkKeyEncoding, DefaultChunkKeyEncoding, and V2ChunkKeyEncoding from zarr.core.chunk_key_encodings

These types can now be imported directly from zarr for better type hints and API clarity.

Also add __all__ exports to zarr.core.group to explicitly declare public types.

Author: Test User

changes/3795.feature.md

@@ -0,0 +1,17 @@
+Create public types for metadata objects
+
+Metadata objects are now available as public types from the main `zarr` module:
+
+- `ArrayV2Metadata` and `ArrayV3Metadata` for array metadata
+- `GroupMetadata` and `ImplicitGroupMarker` for group metadata
+- `ChunkGrid` and `RegularChunkGrid` for chunk grid definitions
+- `ChunkKeyEncoding`, `DefaultChunkKeyEncoding`, and `V2ChunkKeyEncoding` for chunk key encoding strategies
+- `ConsolidatedMetadata` for consolidated metadata storage
+
+These types can now be imported directly from `zarr` for better API clarity and type hints:
+
+```python
+from zarr import ArrayV3Metadata, GroupMetadata, ChunkGrid
+```
+
+Previously, these types were only accessible through private module paths like `zarr.core.metadata` or `zarr.core.group`.

src/zarr/__init__.py

@@ -35,8 +35,21 @@
     zeros_like,
 )
 from zarr.core.array import Array, AsyncArray
+from zarr.core.chunk_grids import ChunkGrid, RegularChunkGrid
+from zarr.core.chunk_key_encodings import (
+    ChunkKeyEncoding,
+    DefaultChunkKeyEncoding,
+    V2ChunkKeyEncoding,
+)
 from zarr.core.config import config
-from zarr.core.group import AsyncGroup, Group
+from zarr.core.group import (
+    AsyncGroup,
+    ConsolidatedMetadata,
+    Group,
+    GroupMetadata,
+    ImplicitGroupMarker,
+)
+from zarr.core.metadata import ArrayV2Metadata, ArrayV3Metadata
 
 # in case setuptools scm screw up and find version to be 0.0.0
 assert not __version__.startswith("0.0.0")
@@ -144,9 +157,19 @@ def set_format(log_format: str) -> None:
 
 __all__ = [
     "Array",
+    "ArrayV2Metadata",
+    "ArrayV3Metadata",
     "AsyncArray",
     "AsyncGroup",
+    "ChunkGrid",
+    "ChunkKeyEncoding",
+    "ConsolidatedMetadata",
+    "DefaultChunkKeyEncoding",
     "Group",
+    "GroupMetadata",
+    "ImplicitGroupMarker",
+    "RegularChunkGrid",
+    "V2ChunkKeyEncoding",
     "__version__",
     "array",
     "config",

src/zarr/core/group.py

@@ -83,6 +83,14 @@
 
 logger = logging.getLogger("zarr.group")
 
+__all__ = [
+    "AsyncGroup",
+    "ConsolidatedMetadata",
+    "Group",
+    "GroupMetadata",
+    "ImplicitGroupMarker",
+]
+
 DefaultT = TypeVar("DefaultT")