Use PEP 562 instead of _ModuleWithDeprecations

newsfragments/2135.bugfix.rst

@@ -0,0 +1 @@
+Allow `trio` to be a `types.ModuleType` and still have deprecated attributes.

src/trio/__init__.py

@@ -112,9 +112,7 @@
 
 from . import _deprecate as _deprecate
 
-_deprecate.enable_attribute_deprecations(__name__)
-
-__deprecated_attributes__: dict[str, _deprecate.DeprecatedAttribute] = {}
+_deprecate.deprecate_attributes(__name__, {})
 
 # Having the public path in .__module__ attributes is important for:
 # - exception names in printed tracebacks

src/trio/_deprecate.py

@@ -3,7 +3,6 @@
 import sys
 import warnings
 from functools import wraps
-from types import ModuleType
 from typing import TYPE_CHECKING, ClassVar, TypeVar
 
 import attrs
@@ -150,28 +149,20 @@ class DeprecatedAttribute:
     instead: object = _not_set
 
 
-class _ModuleWithDeprecations(ModuleType):
-    __deprecated_attributes__: dict[str, DeprecatedAttribute]
-
-    def __getattr__(self, name: str) -> object:
-        if name in self.__deprecated_attributes__:
-            info = self.__deprecated_attributes__[name]
+def deprecate_attributes(
+    module_name: str, deprecated_attributes: dict[str, DeprecatedAttribute]
+) -> None:
+    def __getattr__(name: str) -> object:
+        if name in deprecated_attributes:
+            info = deprecated_attributes[name]
             instead = info.instead
             if instead is DeprecatedAttribute._not_set:
                 instead = info.value
-            thing = f"{self.__name__}.{name}"
+            thing = f"{module_name}.{name}"
             warn_deprecated(thing, info.version, issue=info.issue, instead=instead)
             return info.value
 
         msg = "module '{}' has no attribute '{}'"
-        raise AttributeError(msg.format(self.__name__, name))
-
+        raise AttributeError(msg.format(module_name, name))
 
-def enable_attribute_deprecations(module_name: str) -> None:
-    module = sys.modules[module_name]
-    module.__class__ = _ModuleWithDeprecations
-    assert isinstance(module, _ModuleWithDeprecations)
-    # Make sure that this is always defined so that
-    # _ModuleWithDeprecations.__getattr__ can access it without jumping
-    # through hoops or risking infinite recursion.
-    module.__deprecated_attributes__ = {}
+    sys.modules[module_name].__getattr__ = __getattr__  # type: ignore[method-assign]

src/trio/_tests/module_with_deprecations.py

@@ -1,24 +1,22 @@
 regular = "hi"
 
+import sys
+
 from .. import _deprecate
 
-_deprecate.enable_attribute_deprecations(__name__)
-
-# Make sure that we don't trigger infinite recursion when accessing module
-# attributes in between calling enable_attribute_deprecations and defining
-# __deprecated_attributes__:
-import sys
+_deprecate.deprecate_attributes(
+    __name__,
+    {
+        "dep1": _deprecate.DeprecatedAttribute("value1", "1.1", issue=1),
+        "dep2": _deprecate.DeprecatedAttribute(
+            "value2",
+            "1.2",
+            issue=1,
+            instead="instead-string",
+        ),
+    },
+)
 
 this_mod = sys.modules[__name__]
 assert this_mod.regular == "hi"
-assert not hasattr(this_mod, "dep1")
-
-__deprecated_attributes__ = {
-    "dep1": _deprecate.DeprecatedAttribute("value1", "1.1", issue=1),
-    "dep2": _deprecate.DeprecatedAttribute(
-        "value2",
-        "1.2",
-        issue=1,
-        instead="instead-string",
-    ),
-}
+assert "dep1" not in globals()

src/trio/_tests/test_deprecate.py

@@ -2,6 +2,7 @@
 
 import inspect
 import warnings
+from types import ModuleType
 
 import pytest
 
@@ -244,6 +245,8 @@ def test_module_with_deprecations(recwarn_always: pytest.WarningsRecorder) -> No
     assert module_with_deprecations.regular == "hi"
     assert len(recwarn_always) == 0
 
+    assert type(module_with_deprecations) is ModuleType
+
     filename, lineno = _here()
     assert module_with_deprecations.dep1 == "value1"  # type: ignore[attr-defined]
     got = recwarn_always.pop(DeprecationWarning)