REF: Add back attr passing in concat by attribute

Author: mroeschke

pandas/core/generic.py

@@ -6017,16 +6017,17 @@ def __finalize__(self, other, method: str | None = None, **kwargs) -> Self:
                 object.__setattr__(self, name, getattr(other, name, None))
 
         if method == "concat":
-            objs = kwargs["objs"]
             # propagate attrs only if all concat arguments have the same attrs
-            if all(bool(obj.attrs) for obj in objs):
+            if all(bool(obj.attrs) for obj in other.objs):
                 # all concatenate arguments have non-empty attrs
-                attrs = objs[0].attrs
-                have_same_attrs = all(obj.attrs == attrs for obj in objs[1:])
+                attrs = other.objs[0].attrs
+                have_same_attrs = all(obj.attrs == attrs for obj in other.objs[1:])
                 if have_same_attrs:
                     self.attrs = deepcopy(attrs)
 
-            allows_duplicate_labels = all(x.flags.allows_duplicate_labels for x in objs)
+            allows_duplicate_labels = all(
+                x.flags.allows_duplicate_labels for x in other.objs
+            )
             self.flags.allows_duplicate_labels = allows_duplicate_labels
 
         return self

pandas/core/reshape/concat.py

@@ -5,6 +5,7 @@
 from __future__ import annotations
 
 from collections import abc
+import types
 from typing import (
     TYPE_CHECKING,
     Literal,
@@ -536,7 +537,9 @@ def _get_result(
 
             result = sample._constructor_from_mgr(mgr, axes=mgr.axes)
             result._name = name
-            return result.__finalize__(object(), method="concat", objs=objs)
+            return result.__finalize__(
+                types.SimpleNamespace(objs=objs), method="concat"
+            )
 
         # combine as columns in a frame
         else:
@@ -556,7 +559,7 @@ def _get_result(
             )
             df = cons(data, index=index, copy=False)
             df.columns = columns
-            return df.__finalize__(object(), method="concat", objs=objs)
+            return df.__finalize__(types.SimpleNamespace(objs=objs), method="concat")
 
     # combine block managers
     else:
@@ -595,7 +598,7 @@ def _get_result(
         )
 
         out = sample._constructor_from_mgr(new_data, axes=new_data.axes)
-        return out.__finalize__(object(), method="concat", objs=objs)
+        return out.__finalize__(types.SimpleNamespace(objs=objs), method="concat")
 
 
 def new_axes(

pandas/tests/generic/test_frame.py

@@ -84,9 +84,8 @@ def finalize(self, other, method=None, **kwargs):
                     value = getattr(left, name, "") + "|" + getattr(right, name, "")
                     object.__setattr__(self, name, value)
                 elif method == "concat":
-                    objs = kwargs["objs"]
                     value = "+".join(
-                        [getattr(o, name) for o in objs if getattr(o, name, None)]
+                        [getattr(o, name) for o in other.objs if getattr(o, name, None)]
                     )
                     object.__setattr__(self, name, value)
                 else:

pandas/tests/generic/test_series.py

@@ -94,9 +94,12 @@ def test_metadata_propagation_indiv(self, monkeypatch):
         def finalize(self, other, method=None, **kwargs):
             for name in self._metadata:
                 if method == "concat" and name == "filename":
-                    objs = kwargs["objs"]
                     value = "+".join(
-                        [getattr(obj, name) for obj in objs if getattr(obj, name, None)]
+                        [
+                            getattr(obj, name)
+                            for obj in other.objs
+                            if getattr(obj, name, None)
+                        ]
                     )
                     object.__setattr__(self, name, value)
                 else: