[GitHub] [iceberg] samredai commented on a diff in pull request #4480: Python: Refactor to use common decimal and datetime util

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

samredai commented on code in PR #4480:
URL: https://github.com/apache/iceberg/pull/4480#discussion_r841348108


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python/src/iceberg/utils/decimal.py:
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@@ -0,0 +1,70 @@
+#  Licensed to the Apache Software Foundation (ASF) under one
+#  or more contributor license agreements.  See the NOTICE file
+#  distributed with this work for additional information
+#  regarding copyright ownership.  The ASF licenses this file
+#  to you under the Apache License, Version 2.0 (the
+#  "License"); you may not use this file except in compliance
+#  with the License.  You may obtain a copy of the License at
+#
+#    http://www.apache.org/licenses/LICENSE-2.0
+#
+#  Unless required by applicable law or agreed to in writing,
+#  software distributed under the License is distributed on an
+#  "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+#  KIND, either express or implied.  See the License for the
+#  specific language governing permissions and limitations
+#  under the License.
+
+"""Helper methods for working with Python Decimals
+"""
+from decimal import Decimal
+from typing import Union
+
+
+def decimal_to_unscaled(value: Decimal) -> int:
+    """Get an unscaled value given a Decimal value
+
+    Args:
+        value (Decimal): A Decimal instance
+
+    Returns:
+        int: The unscaled value
+    """
+    sign, digits, _ = value.as_tuple()
+    return int(Decimal((sign, digits, 0)).to_integral_value())
+
+
+def unscaled_to_decimal(unscaled: int, scale: int) -> Decimal:
+    """Get a scaled Decimal value given an unscaled value and a scale
+
+    Args:
+        unscaled (int): An unscaled value
+        scale (int): A scale to set for the returned Decimal instance
+
+    Returns:
+        Decimal: A scaled Decimal instance
+    """
+    sign, digits, _ = Decimal(unscaled).as_tuple()
+    return Decimal((sign, digits, -scale))
+
+
+def min_size(value: Union[int, Decimal]) -> int:
+    """Returns the minimum number of bytes needed to serialize a decimal or unscaled value
+
+    Args:
+        value (int | Decimal): a Decimal value or unscaled int value
+
+    Returns:
+        int: the minimum number of bytes needed to serialize the value
+    """
+    if isinstance(value, int):
+        return (value.bit_length() + 7) // 8
+    elif isinstance(value, Decimal):
+        return (decimal_to_unscaled(value).bit_length() + 7) // 8
+
+    raise ValueError(f"Unsupported value: {value}")
+
+
+def decimal_to_bytes(value: Decimal) -> bytes:
+    unscaled_value = decimal_to_unscaled(value)

Review Comment:
   Suggesting a docstring here:
   
       """Returns a byte representation of a decimal
   
       Args:
           value (Decimal): a decimal value
       Returns:
           bytes: A byte representation of the decimal unscaled
       """



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