Implement ContextManager for AttrCleaner

sebastinas · sebastinas · commit 3ad203dc1ec9 · 2022-08-29T18:17:47.000+02:00
Also extend some documentation.
diff --git a/bpython/autocomplete.py b/bpython/autocomplete.py
@@ -458,8 +458,9 @@ def attr_lookup(self, obj: Any, expr: str, attr: str) -> List:
         return matches
 
     def list_attributes(self, obj: Any) -> List[str]:
-        # TODO: re-implement dir using getattr_static to avoid using
-        # AttrCleaner here?
+        # TODO: re-implement dir without AttrCleaner here
+        #
+        # Note: accessing `obj.__dir__` via `getattr_static` is not side-effect free.
         with inspection.AttrCleaner(obj):
             return dir(obj)
 
diff --git a/bpython/inspection.py b/bpython/inspection.py
@@ -26,7 +26,7 @@
 import pydoc
 import re
 from dataclasses import dataclass
-from typing import Any, Callable, Optional, Type, Dict, List
+from typing import Any, Callable, Optional, Type, Dict, List, ContextManager
 from types import MemberDescriptorType, TracebackType
 from ._typing_compat import Literal
 
@@ -54,9 +54,11 @@ class FuncProps:
     is_bound_method: bool
 
 
-class AttrCleaner:
+class AttrCleaner(ContextManager[None]):
     """A context manager that tries to make an object not exhibit side-effects
-    on attribute lookup."""
+    on attribute lookup.
+
+    Unless explicitely required, prefer `getattr_safe`."""
 
     def __init__(self, obj: Any) -> None:
         self._obj = obj
@@ -351,7 +353,7 @@ def get_encoding_file(fname: str) -> str:
 
 
 def getattr_safe(obj: Any, name: str) -> Any:
-    """side effect free getattr (calls getattr_static)."""
+    """Side effect free getattr (calls getattr_static)."""
     result = inspect.getattr_static(obj, name)
     # Slots are a MemberDescriptorType
     if isinstance(result, MemberDescriptorType):
