✨ Allow annotated parsing with a subclass of Path

tests/test_annotated.py

@@ -1,3 +1,6 @@
+import sys
+from pathlib import Path
+
 import typer
 from typer.testing import CliRunner
 from typing_extensions import Annotated
@@ -76,3 +79,22 @@ def cmd(force: Annotated[bool, typer.Option("--force")] = False):
     result = runner.invoke(app, ["--force"])
     assert result.exit_code == 0, result.output
     assert "Forcing operation" in result.output
+
+
+def test_annotated_custom_path():
+    app = typer.Typer()
+
+    class CustomPath(Path):
+        # Subclassing Path was not fully supported before 3.12
+        # https://docs.python.org/3.12/whatsnew/3.12.html
+        if sys.version_info < (3, 12):
+            _flavour = type(Path())._flavour
+
+    @app.command()
+    def custom_parser(
+        my_path: Annotated[CustomPath, typer.Argument(parser=CustomPath)],
+    ):
+        assert isinstance(my_path, CustomPath)
+
+    result = runner.invoke(app, "/some/quirky/path/implementation")
+    assert result.exit_code == 0

typer/main.py

@@ -622,7 +622,9 @@ def determine_type_convertor(type_: Any) -> Optional[Callable[[Any], Any]]:
 
 def param_path_convertor(value: Optional[str] = None) -> Optional[Path]:
     if value is not None:
-        return Path(value)
+        # allow returning any subclass of Path created by an annotated parser without converting
+        # it back to a Path
+        return value if isinstance(value, Path) else Path(value)
     return None