REF: de-duplicate _wrap_joined_index in MultiIndex (pandas-dev#36313)

Author: jbrockmendel

pandas/core/indexes/base.py

@@ -3876,7 +3876,10 @@ def _join_monotonic(self, other, how="left", return_indexers=False):
             return join_index
 
     def _wrap_joined_index(self, joined, other):
-        name = get_op_result_name(self, other)
+        if isinstance(self, ABCMultiIndex):
+            name = self.names if self.names == other.names else None
+        else:
+            name = get_op_result_name(self, other)
         return self._constructor(joined, name=name)
 
     # --------------------------------------------------------------------

pandas/core/indexes/multi.py

@@ -1,3 +1,4 @@
+from functools import wraps
 from sys import getsizeof
 from typing import (
     TYPE_CHECKING,
@@ -152,6 +153,25 @@ def _codes_to_ints(self, codes):
         return np.bitwise_or.reduce(codes, axis=1)
 
 
+def names_compat(meth):
+    """
+    A decorator to allow either `name` or `names` keyword but not both.
+
+    This makes it easier to share code with base class.
+    """
+
+    @wraps(meth)
+    def new_meth(self_or_cls, *args, **kwargs):
+        if "name" in kwargs and "names" in kwargs:
+            raise TypeError("Can only provide one of `names` and `name`")
+        elif "name" in kwargs:
+            kwargs["names"] = kwargs.pop("name")
+
+        return meth(self_or_cls, *args, **kwargs)
+
+    return new_meth
+
+
 class MultiIndex(Index):
     """
     A multi-level, or hierarchical, index object for pandas objects.
@@ -449,6 +469,7 @@ def from_arrays(cls, arrays, sortorder=None, names=lib.no_default) -> "MultiInde
         )
 
     @classmethod
+    @names_compat
     def from_tuples(
         cls,
         tuples,
@@ -3635,10 +3656,6 @@ def delete(self, loc):
             verify_integrity=False,
         )
 
-    def _wrap_joined_index(self, joined, other):
-        names = self.names if self.names == other.names else None
-        return self._constructor(joined, names=names)
-
     @doc(Index.isin)
     def isin(self, values, level=None):
         if level is None: