[GitHub] [iceberg] rdblue commented on a diff in pull request #4908: [Python] add identity transform

[GitBox <gi...@apache.org>]

rdblue commented on code in PR #4908:
URL: https://github.com/apache/iceberg/pull/4908#discussion_r895225327


##########
python/src/iceberg/transforms.py:
##########
@@ -224,6 +227,80 @@ def hash(self, value: UUID) -> int:
         )
 
 
+def _base64encode(buffer: bytes) -> str:
+    """Converts bytes to base64 string"""
+    return base64.b64encode(buffer).decode("ISO-8859-1")
+
+
+class IdentityTransform(Transform[S, S]):
+    """Transforms a value into itself.
+
+    Example:
+        >>> transform = IdentityTransform(StringType())
+        >>> transform.apply('hello-world')
+        'hello-world'
+    """
+
+    def __init__(self, source_type: IcebergType):
+        super().__init__(
+            "identity",
+            f"transforms.identity(source_type={repr(source_type)})",
+        )
+        self._type = source_type
+
+    def apply(self, value: Optional[S]) -> Optional[S]:
+        return value
+
+    def can_transform(self, source: IcebergType) -> bool:
+        return source.is_primitive
+
+    def result_type(self, source: IcebergType) -> IcebergType:
+        return source
+
+    @property
+    def preserves_order(self) -> bool:
+        return True
+
+    def satisfies_order_of(self, other: Transform) -> bool:
+        """ordering by value is the same as long as the other preserves order"""
+        return other.preserves_order
+
+    def to_human_string(self, value: Optional[S]) -> str:
+        return self._human_string(value)
+
+    @singledispatchmethod
+    def _human_string(self, value: Optional[S]) -> str:

Review Comment:
   Minor: There's no need for these to be in the class, and it's actually faster if they are simple methods.



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