From 902a7dd6d567a7c184fb8f3fc3b1907e18037356 Mon Sep 17 00:00:00 2001
From: Brock <jbrockmendel@gmail.com>
Date: Mon, 14 Sep 2020 11:19:31 -0700
Subject: [PATCH] REF: share code for __setitem__

---
 pandas/core/arrays/_mixins.py      | 12 ++++++++++++
 pandas/core/arrays/categorical.py  | 14 --------------
 pandas/core/arrays/datetimelike.py |  4 +---
 pandas/core/arrays/numpy_.py       |  8 --------
 4 files changed, 13 insertions(+), 25 deletions(-)

diff --git a/pandas/core/arrays/_mixins.py b/pandas/core/arrays/_mixins.py
index e9d8671b69c78..284dd31ffcb59 100644
--- a/pandas/core/arrays/_mixins.py
+++ b/pandas/core/arrays/_mixins.py
@@ -9,6 +9,7 @@
 from pandas.core.algorithms import take, unique
 from pandas.core.array_algos.transforms import shift
 from pandas.core.arrays.base import ExtensionArray
+from pandas.core.indexers import check_array_indexer
 
 _T = TypeVar("_T", bound="NDArrayBackedExtensionArray")
 
@@ -156,3 +157,14 @@ def _validate_shift_value(self, fill_value):
         # TODO: after deprecation in datetimelikearraymixin is enforced,
         #  we can remove this and ust validate_fill_value directly
         return self._validate_fill_value(fill_value)
+
+    def __setitem__(self, key, value):
+        key = self._validate_setitem_key(key)
+        value = self._validate_setitem_value(value)
+        self._ndarray[key] = value
+
+    def _validate_setitem_key(self, key):
+        return check_array_indexer(self, key)
+
+    def _validate_setitem_value(self, value):
+        return value
diff --git a/pandas/core/arrays/categorical.py b/pandas/core/arrays/categorical.py
index 45623f182144b..0d73f45f1a395 100644
--- a/pandas/core/arrays/categorical.py
+++ b/pandas/core/arrays/categorical.py
@@ -1884,20 +1884,6 @@ def __getitem__(self, key):
             return result
         return self._from_backing_data(result)
 
-    def __setitem__(self, key, value):
-        """
-        Item assignment.
-
-        Raises
-        ------
-        ValueError
-            If (one or more) Value is not in categories or if a assigned
-            `Categorical` does not have the same categories
-        """
-        key = self._validate_setitem_key(key)
-        value = self._validate_setitem_value(value)
-        self._ndarray[key] = value
-
     def _validate_setitem_value(self, value):
         value = extract_array(value, extract_numpy=True)
 
diff --git a/pandas/core/arrays/datetimelike.py b/pandas/core/arrays/datetimelike.py
index 377996344dbbc..5c3ef2957073a 100644
--- a/pandas/core/arrays/datetimelike.py
+++ b/pandas/core/arrays/datetimelike.py
@@ -609,9 +609,7 @@ def __setitem__(
         if no_op:
             return
 
-        value = self._validate_setitem_value(value)
-        key = check_array_indexer(self, key)
-        self._ndarray[key] = value
+        super().__setitem__(key, value)
         self._maybe_clear_freq()
 
     def _maybe_clear_freq(self):
diff --git a/pandas/core/arrays/numpy_.py b/pandas/core/arrays/numpy_.py
index d3fa87d5ea7ff..61ffa28d31ba0 100644
--- a/pandas/core/arrays/numpy_.py
+++ b/pandas/core/arrays/numpy_.py
@@ -259,11 +259,6 @@ def __getitem__(self, item):
             result = type(self)(result)
         return result
 
-    def __setitem__(self, key, value) -> None:
-        key = self._validate_setitem_key(key)
-        value = self._validate_setitem_value(value)
-        self._ndarray[key] = value
-
     def _validate_setitem_value(self, value):
         value = extract_array(value, extract_numpy=True)
 
@@ -271,9 +266,6 @@ def _validate_setitem_value(self, value):
             value = np.asarray(value, dtype=self._ndarray.dtype)
         return value
 
-    def _validate_setitem_key(self, key):
-        return check_array_indexer(self, key)
-
     def isna(self) -> np.ndarray:
         return isna(self._ndarray)