src/otk/annotation: implement support for python 3.9

as we explicitly support python 3.9 and the implementations
of pathlib are different we need to have special support
as we want to inherit from pathlib.

src/otk/annotation.py

@@ -1,7 +1,8 @@
 import copy
 import os
 import pathlib
-from typing import TypeVar, Generic, Any
+import sys
+from typing import TypeVar, Generic, Any, Optional
 
 
 class AnnotatedBase:
@@ -21,7 +22,7 @@ def __init__(self) -> None:
             for key, value in self.items():
                 self[key] = self.deep_convert(value)
 
-    def get_annotation(self, key: str, default: Any | None = None) -> Any | None:
+    def get_annotation(self, key: str, default: Any = None) -> Any:
         if key in self._otk_annotations:
             return self._otk_annotations[key]
         return default
@@ -176,29 +177,25 @@ def squash_annotations(cls, annotation_list: list) -> dict:
 
 
 class AnnotatedList(Generic[AnnotatedListT], AnnotatedBase, list):
-    def __init__(self, seq: list[Any] | None = None) -> None:
+    def __init__(self, seq: Optional[list[Any]] = None) -> None:
         if seq is None:
             seq = []
         list.__init__(self, seq)
         AnnotatedBase.__init__(self)
 
 
 class AnnotatedDict(Generic[AnnotatedDictKeyT, AnnotatedDictVarT], AnnotatedBase, dict):
-    def __init__(self, seq: dict[Any, Any] | None = None, **kwargs: dict[Any, Any]) -> None:
+    def __init__(self, seq: Optional[dict[Any, Any]] = None, **kwargs: dict[Any, Any]) -> None:
         if seq is None:
             seq = {}
         dict.__init__(self, seq, **kwargs)
         AnnotatedBase.__init__(self)
 
 
-class AnnotatedPath(AnnotatedBase, pathlib.Path):
-    def __init__(self, *args: Any, **kwargs: Any) -> None:
-        pathlib.Path.__init__(self, *args, **kwargs)
-        AnnotatedBase.__init__(self)
-
+class AnnotatedPathBase(AnnotatedBase):
     def fspath_with_include(self) -> str:
         src = None
-        filename = os.path.relpath(os.fspath(self), self._basedir)
+        filename = os.path.relpath(os.fspath(str(self)), self._basedir)
         try:
             src = self.get_annotation("src")
         except KeyError:
@@ -208,6 +205,18 @@ def fspath_with_include(self) -> str:
         return filename
 
 
+if sys.version_info >= (3, 10):
+    class AnnotatedPath(AnnotatedPathBase, pathlib.Path):
+        def __init__(self, *args: Any, **kwargs: Any) -> None:
+            pathlib.Path.__init__(self, *args, **kwargs)
+            AnnotatedPathBase.__init__(self)
+else:
+    class AnnotatedPath(AnnotatedPathBase, pathlib.PosixPath):  # pylint: disable=abstract-method
+        def __init__(self, *args: Any) -> None:  # pylint: disable=W0613
+            pathlib.PosixPath.__init__(self)
+            AnnotatedPathBase.__init__(self)
+
+
 class AnnotatedStr(AnnotatedBase, str):
     def __init__(self, *args: str) -> None:  # pylint: disable=W0613
         str.__init__(self)