feat: Support sub-extensions with custom hooks

src/_griffe/extensions/base.py

@@ -8,7 +8,7 @@
 from importlib.util import module_from_spec, spec_from_file_location
 from inspect import isclass
 from pathlib import Path
-from typing import TYPE_CHECKING, Any, Dict, Type, Union
+from typing import TYPE_CHECKING, Any, Dict, Self, Type, Union
 
 from _griffe.agents.nodes.ast import ast_children, ast_kind
 from _griffe.exceptions import ExtensionNotLoadedError
@@ -28,6 +28,8 @@
 class Extension:
     """Base class for Griffe extensions."""
 
+    sub_extensions: tuple[SubExtension, ...] = ()
+
     def visit(self, node: ast.AST) -> None:
         """Visit a node.
 
@@ -277,6 +279,17 @@ def on_wildcard_expansion(
         """
 
 
+class SubExtension:
+    """Base class for Griffe sub-extensions."""
+
+    namespace: str
+
+    def __init_subclass__(cls) -> None:
+        if not hasattr(cls, "namespace") or not cls.namespace:
+            cls.namespace = cls.__name__
+
+
+
 LoadableExtensionType = Union[str, Dict[str, Any], Extension, Type[Extension]]
 """All the types that can be passed to `load_extensions`."""
 
@@ -312,6 +325,17 @@ def call(self, event: str, **kwargs: Any) -> None:
         for extension in self._extensions:
             getattr(extension, event)(**kwargs)
 
+    def subcall(self, namespace: str, event: str, **kwargs: Any) -> None:
+        """Call the sub-extension hook for the given event.
+
+        Parameters:
+            event: The triggered event.
+            **kwargs: Arguments passed to the hook.
+        """
+        for extension in self._extensions:
+            for sub_extension in extension.sub_extensions:
+                if sub_extension.namespace == namespace:
+                    getattr(sub_extension, event)(**kwargs)
 
 builtin_extensions: set[str] = {
     "dataclasses",