Update xarray/core/extension_array.py

Co-authored-by: Ilan Gold <ilanbassgold@gmail.com>
pydata · dcherian · May 8, 2025 · May 1, 2025 · May 7, 2025 · May 7, 2025
commit 93405b81ab62468d29f0d0f1c952f6a7aaf3e295
diff --git a/xarray/core/extension_array.py b/xarray/core/extension_array.py
@@ -144,11 +144,8 @@ def __array__(
             return np.asarray(self.array, dtype=dtype)
 
     def __getattr__(self, attr: str) -> Any:
-        #  without __deepcopy__ or __copy__, the object is first constructed and then the sub-objects are attached:
-        # "A shallow copy constructs a new compound object and then (to the extent possible) inserts references into it to the objects found in the original" +
-        # "A deep copy constructs a new compound object and then, recursively, inserts copies into it of the objects found in the original."
-        # So without array, this method then calls getattr for "array" again while looking for __setstate__
-        # (which is apparently the first thing sought in copy.copy from the under-construction copied object)
-        # because of self.array. __getattribute__ bypasses the lookup mechanism of __getattr__.
-        # See stackoverflow.com/questions/40583131/python-deepcopy-with-custom-getattr-and-setattr as well.
+        #  with __deepcopy__ or __copy__, the object is first constructed and then the sub-objects are attached (see https://docs.python.org/3/library/copy.html)
+        # Thus, if we didn't have `super().__getattribute__("array")` this method would call `self.array` (i.e., `getattr(self, "array")`) again while looking for `__setstate__`
+        # (which is apparently the first thing sought in copy.copy from the under-construction copied object),
+        # which would cause a recursion error since `array` is not present on the object when it is being constructed during `__{deep}copy__`.
         return getattr(super().__getattribute__("array"), attr)