make property in base class StorageExtensionDtype as well

Author: jorisvandenbossche

pandas/core/dtypes/base.py

@@ -459,7 +459,7 @@ class StorageExtensionDtype(ExtensionDtype):
     _metadata = ("storage",)
 
     def __init__(self, storage: str | None = None) -> None:
-        self.storage = storage
+        self._storage = storage
 
     def __repr__(self) -> str:
         return f"{self.name}[{self.storage}]"
@@ -480,6 +480,10 @@ def __hash__(self) -> int:
     def na_value(self) -> libmissing.NAType:
         return libmissing.NA
 
+    @property
+    def storage(self) -> str:
+        return self._storage
+
 
 @set_module("pandas.api.extensions")
 def register_extension_dtype(cls: type_t[ExtensionDtypeT]) -> type_t[ExtensionDtypeT]: