[GitHub] [spark] zhengruifeng commented on a diff in pull request #38806: [SPARK-41268][CONNECT][PYTHON] Refactor "Column" for API Compatibility

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

zhengruifeng commented on code in PR #38806:
URL: https://github.com/apache/spark/pull/38806#discussion_r1033087883


##########
python/pyspark/sql/connect/column.py:
##########
@@ -30,53 +30,34 @@
 
 def _bin_op(
     name: str, doc: str = "binary function", reverse: bool = False
-) -> Callable[["Column", Any], "Expression"]:
-    def _(self: "Column", other: Any) -> "Expression":
+) -> Callable[["Column", Any], "Column"]:
+    def _(self: "Column", other: Any) -> "Column":
         from pyspark.sql.connect._typing import PrimitiveType
+        from pyspark.sql.connect.functions import lit
 
         if isinstance(other, get_args(PrimitiveType)):
-            other = LiteralExpression(other)
+            other = lit(other)
         if not reverse:
-            return ScalarFunctionExpression(name, self, other)
+            return scalar_function(name, self, other)
         else:
-            return ScalarFunctionExpression(name, other, self)
+            return scalar_function(name, other, self)
 
     return _
 
 
+def scalar_function(op: str, *args: "Column") -> "Column":
+    return Column(ScalarFunctionExpression(op, *args))
+
+
+def sql_expression(expr: str) -> "Column":
+    return Column(SQLExpression(expr))
+
+
 class Expression(object):

Review Comment:
   nit: maybe we can have a separate file `expressions.py` for Expression?



##########
python/pyspark/sql/connect/column.py:
##########
@@ -314,3 +323,70 @@ def to_plan(self, session: "SparkConnectClient") -> proto.Expression:
 
     def __str__(self) -> str:
         return f"({self._op} ({', '.join([str(x) for x in self._args])}))"
+
+
+class Column(object):
+    """
+    A column in a DataFrame. Column can refer to different things based on the
+    wrapped expression. Some common examples include attribute references, functions,
+    literals, etc.
+
+    .. versionadded:: 3.4.0
+    """
+
+    def __init__(self, expr: Expression) -> None:
+        self._expr = expr
+
+    __gt__ = _bin_op(">")
+    __lt__ = _bin_op("<")
+    __add__ = _bin_op("+")
+    __sub__ = _bin_op("-")
+    __mul__ = _bin_op("*")
+    __div__ = _bin_op("/")
+    __truediv__ = _bin_op("/")
+    __mod__ = _bin_op("%")
+    __radd__ = _bin_op("+", reverse=True)
+    __rsub__ = _bin_op("-", reverse=True)
+    __rmul__ = _bin_op("*", reverse=True)
+    __rdiv__ = _bin_op("/", reverse=True)
+    __rtruediv__ = _bin_op("/", reverse=True)
+    __pow__ = _bin_op("pow")
+    __rpow__ = _bin_op("pow", reverse=True)
+    __ge__ = _bin_op(">=")
+    __le__ = _bin_op("<=")
+    # __eq__ = _bin_op("==")  # ignore [assignment]
+
+    def __eq__(self, other: Any) -> "Column":  # type: ignore[override]
+        """Returns a binary expression with the current column as the left
+        side and the other expression as the right side.
+        """
+        from pyspark.sql.connect._typing import PrimitiveType
+        from pyspark.sql.connect.functions import lit
+
+        if isinstance(other, get_args(PrimitiveType)):
+            other = lit(other)
+        return scalar_function("==", self, other)
+
+    def to_plan(self, session: "SparkConnectClient") -> proto.Expression:
+        return self._expr.to_plan(session)

Review Comment:
   now it think it is fine to just use expressions in proto messages.



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