FIX-#5380: Fix warning about setting _cache attribute. (#5381)

Signed-off-by: mvashishtha <mahesh@ponder.io>

modin/pandas/dataframe.py

@@ -56,6 +56,7 @@
     from_pandas,
     from_non_pandas,
     broadcast_item,
+    SET_DATAFRAME_ATTRIBUTE_WARNING,
 )
 from . import _update_engine
 from .iterator import PartitionIterator
@@ -2662,7 +2663,9 @@ def __setattr__(self, key, value):
         # - `_query_compiler`, which Modin initializes before it appears in
         #   __dict__
         # - `_siblings`, which Modin initializes before it appears in __dict__
-        if key in ["_query_compiler", "_siblings"] or key in self.__dict__:
+        # - `_cache`, which pandas.cache_readonly uses to cache properties
+        #   before it appears in __dict__.
+        if key in ("_query_compiler", "_siblings", "_cache") or key in self.__dict__:
             pass
         elif key in self and key not in dir(self):
             self.__setitem__(key, value)
@@ -2672,8 +2675,7 @@ def __setattr__(self, key, value):
             return
         elif is_list_like(value) and key not in ["index", "columns"]:
             warnings.warn(
-                "Modin doesn't allow columns to be created via a new attribute name - see "
-                + "https://pandas.pydata.org/pandas-docs/stable/indexing.html#attribute-access",
+                SET_DATAFRAME_ATTRIBUTE_WARNING,
                 UserWarning,
             )
         object.__setattr__(self, key, value)

modin/pandas/test/dataframe/test_iter.py

@@ -30,6 +30,7 @@
     create_test_dfs,
     test_data,
 )
+from modin.pandas.utils import SET_DATAFRAME_ATTRIBUTE_WARNING
 from modin.config import NPartitions
 from modin.test.test_utils import warns_that_defaulting_to_pandas
 
@@ -232,6 +233,14 @@ def test___repr__():
     assert repr(pandas_df) == repr(modin_df)
 
 
+def test___repr__does_not_raise_attribute_column_warning():
+    # See https://github.com/modin-project/modin/issues/5380
+    df = pd.DataFrame([1])
+    with warnings.catch_warnings():
+        warnings.filterwarnings(action="error", message=SET_DATAFRAME_ATTRIBUTE_WARNING)
+        repr(df)
+
+
 @pytest.mark.parametrize("data", test_data_values, ids=test_data_keys)
 def test_inplace_series_ops(data):
     pandas_df = pandas.DataFrame(data)
@@ -294,16 +303,14 @@ def test___setattr__mutating_column():
     # and adds the provided list as a new attribute and not a column.
     with pytest.warns(
         UserWarning,
-        match="Modin doesn't allow columns to be created via a new attribute name - see "
-        + "https://pandas.pydata.org/pandas-docs/stable/indexing.html#attribute-access",
+        match=SET_DATAFRAME_ATTRIBUTE_WARNING,
     ):
         modin_df.col1 = [4]
 
     with warnings.catch_warnings():
         warnings.filterwarnings(
             action="error",
-            message="Modin doesn't allow columns to be created via a new attribute name - see "
-            + "https://pandas.pydata.org/pandas-docs/stable/indexing.html#attribute-access",
+            message=SET_DATAFRAME_ATTRIBUTE_WARNING,
         )
         modin_df.col1 = [5]
         modin_df.new_attr = 6

modin/pandas/utils.py

@@ -32,6 +32,11 @@
 {returns}
 """
 
+SET_DATAFRAME_ATTRIBUTE_WARNING = (
+    "Modin doesn't allow columns to be created via a new attribute name - see "
+    + "https://pandas.pydata.org/pandas-docs/stable/indexing.html#attribute-access"
+)
+
 
 def from_non_pandas(df, index, columns, dtype):
     """