[AIR] Make PathPartitionScheme a dataclass (#28390)

Signed-off-by: Balaji Veeramani <bveeramani@berkeley.edu>

python/ray/data/datasource/partitioning.py

@@ -1,3 +1,4 @@
+from dataclasses import dataclass
 import posixpath
 from enum import Enum
 from typing import (
@@ -35,67 +36,43 @@ class PartitionStyle(str, Enum):
 
 
 @DeveloperAPI
+@dataclass
 class Partitioning:
     """Partition scheme used to describe path-based partitions.
 
     Path-based partition formats embed all partition keys and values directly in
     their dataset file paths.
+
+    Attributes:
+        style: The partition style - may be either HIVE or DIRECTORY.
+        base_dir: "/"-delimited base directory that all partitioned paths should
+            exist under (exclusive). File paths either outside of, or at the first
+            level of, this directory will be considered unpartitioned. Specify
+            `None` or an empty string to search for partitions in all file path
+            directories.
+        field_names: The partition key field names (i.e. column names for tabular
+            datasets). When non-empty, the order and length of partition key
+            field names must match the order and length of partition values.
+            Required when parsing DIRECTORY partitioned paths or generating
+            HIVE partitioned paths.
+        filesystem: Filesystem that will be used for partition path file I/O.
     """
 
-    def __init__(
-        self,
-        style: PartitionStyle,
-        base_dir: Optional[str] = None,
-        field_names: Optional[List[str]] = None,
-        filesystem: Optional["pyarrow.fs.FileSystem"] = None,
-    ):
-        """Creates a new path-based dataset partition scheme.
+    style: PartitionStyle
+    base_dir: Optional[str] = None
+    field_names: Optional[List[str]] = None
+    filesystem: Optional["pyarrow.fs.FileSystem"] = None
 
-        Args:
-            style: The partition style - may be either HIVE or DIRECTORY.
-            base_dir: "/"-delimited base directory that all partitioned paths should
-                exist under (exclusive). File paths either outside of, or at the first
-                level of, this directory will be considered unpartitioned. Specify
-                `None` or an empty string to search for partitions in all file path
-                directories.
-            field_names: The partition key field names (i.e. column names for tabular
-                datasets). When non-empty, the order and length of partition key
-                field names must match the order and length of partition values.
-                Required when parsing DIRECTORY partitioned paths or generating
-                HIVE partitioned paths.
-            filesystem: Filesystem that will be used for partition path file I/O.
-        """
-        self._style = style
-        self._base_dir = base_dir or ""
-        self._field_names = field_names
-        self._filesystem = filesystem
+    def __post_init__(self):
+        if self.base_dir is None:
+            self.base_dir = ""
         self._normalize_base_dir()
 
-    @property
-    def style(self) -> PartitionStyle:
-        """Gets the path partitioning style."""
-        return self._style
-
-    @property
-    def base_dir(self) -> str:
-        """Gets the original base directory supplied during object construction."""
-        return self._base_dir
-
     @property
     def normalized_base_dir(self) -> str:
         """Returns the base directory normalized for compatibility with a filesystem."""
         return self._normalized_base_dir
 
-    @property
-    def field_names(self) -> Optional[List[str]]:
-        """Gets the partition key field names."""
-        return self._field_names
-
-    @property
-    def filesystem(self) -> Optional["pyarrow.fs.FileSystem"]:
-        """Gets the original filesystem supplied during object construction."""
-        return self._filesystem
-
     @property
     def resolved_filesystem(self) -> "pyarrow.fs.FileSystem":
         """Returns the filesystem resolved for compatibility with a base directory."""
@@ -114,8 +91,8 @@ def _normalize_base_dir(self):
         )
 
         paths, self._resolved_filesystem = _resolve_paths_and_filesystem(
-            self._base_dir,
-            self._filesystem,
+            self.base_dir,
+            self.filesystem,
         )
         assert (
             len(paths) == 1