feat: Implement extension

Author: pawamoy

pyproject.toml

@@ -27,7 +27,9 @@ classifiers = [
     "Topic :: Utilities",
     "Typing :: Typed",
 ]
-dependencies = []
+dependencies = [
+    "griffe>=0.38",
+]
 
 [project.urls]
 Homepage = "https://mkdocstrings.github.io/griffe-inherited-docstrings"

src/griffe_inherited_docstrings/__init__.py

@@ -5,4 +5,6 @@
 
 from __future__ import annotations
 
-__all__: list[str] = []
+from griffe_inherited_docstrings.extension import InheritDocstringsExtension
+
+__all__: list[str] = ["InheritDocstringsExtension"]

src/griffe_inherited_docstrings/extension.py

@@ -0,0 +1,45 @@
+"""The Griffe extension."""
+
+from __future__ import annotations
+
+import contextlib
+from typing import TYPE_CHECKING
+
+from griffe import Extension
+from griffe.exceptions import AliasResolutionError
+
+if TYPE_CHECKING:
+    from griffe import Docstring, Module, Object
+
+
+def _inherited_docstring(obj: Object) -> Docstring | None:
+    for parent_class in obj.parent.mro():  # type: ignore[union-attr]
+        try:
+            if docstring := parent_class.members[obj.name].docstring:
+                return docstring
+        except KeyError:
+            pass
+    return None
+
+
+def _inherit_docstrings(obj: Object) -> None:
+    if obj.is_module:
+        for member in obj.members.values():
+            if not member.is_alias:
+                with contextlib.suppress(AliasResolutionError):
+                    _inherit_docstrings(member)  # type: ignore[arg-type]
+    elif obj.is_class:
+        for member in obj.members.values():
+            if not member.is_alias:
+                if member.docstring is None and (inherited := _inherited_docstring(member)):  # type: ignore[arg-type]
+                    member.docstring = inherited
+                if member.is_class:
+                    _inherit_docstrings(member)  # type: ignore[arg-type]
+
+
+class InheritDocstringsExtension(Extension):
+    """Griffe extension for inheriting docstrings."""
+
+    def on_package_loaded(self, *, pkg: Module) -> None:
+        """Inherit docstrings from parent classes once the whole package is loaded."""
+        _inherit_docstrings(pkg)

tests/test_extension.py

@@ -0,0 +1,28 @@
+"""Tests for the extension."""
+
+from __future__ import annotations
+
+from griffe.extensions import Extensions
+from griffe.tests import temporary_visited_package
+
+from griffe_inherited_docstrings import InheritDocstringsExtension
+
+
+def test_inherit_docstrings() -> None:
+    """Inherit docstrings from parent classes."""
+    with temporary_visited_package(
+        "package",
+        modules={
+            "__init__.py": """
+                class Parent:
+                    def method(self):
+                        '''Docstring from parent method.'''
+
+                class Child(Parent):
+                    def method(self):
+                        ...
+            """,
+        },
+        extensions=Extensions(InheritDocstringsExtension()),
+    ) as package:
+        assert package["Child.method"].docstring.value == package["Parent.method"].docstring.value