Test fixes, examples cleanup

docs/source/examples/01_basics/03_containers.rst

@@ -18,7 +18,7 @@ container types; such as ``typing.List[T]`` or ``typing.Tuple[T1, T2]``. In Pyth
         import dataclasses
         import enum
         import pathlib
-        from typing import Optional, Tuple
+        from typing import Tuple
 
         import tyro
 

docs/source/examples/01_basics/04_enums.rst

@@ -15,8 +15,6 @@ We can generate argument parsers from more advanced type annotations, like enums
 
         import dataclasses
         import enum
-        import pathlib
-        from typing import Optional, Tuple
 
         import tyro
 

docs/source/examples/01_basics/06_literals.rst

@@ -15,7 +15,7 @@ Choices
 
         import dataclasses
         import enum
-        from typing import Literal, Optional, Tuple, Union
+        from typing import Literal
 
         import tyro
 

examples/01_basics/03_containers.py

@@ -13,7 +13,7 @@
 import dataclasses
 import enum
 import pathlib
-from typing import Optional, Tuple
+from typing import Tuple
 
 import tyro
 

examples/01_basics/04_enums.py

@@ -10,8 +10,6 @@
 
 import dataclasses
 import enum
-import pathlib
-from typing import Optional, Tuple
 
 import tyro
 

examples/01_basics/06_literals.py

@@ -8,7 +8,7 @@
 
 import dataclasses
 import enum
-from typing import Literal, Optional, Tuple, Union
+from typing import Literal
 
 import tyro
 

tests/test_dcargs.py

@@ -491,14 +491,12 @@ def main(x: Callable[[int], int] = lambda x: x * 2) -> Callable[[int], int]:
 
 
 def test_fixed_dataclass_type():
-    @dataclasses.dataclass
-    class Dummy:
-        pass
+    dummy = lambda: 5  # noqa
 
-    def main(x: Callable = Dummy) -> Callable:
+    def main(x: Callable = dummy) -> Callable:
         return x
 
-    assert tyro.cli(main, args=[]) is Dummy
+    assert tyro.cli(main, args=[]) is dummy
     with pytest.raises(SystemExit):
         tyro.cli(main, args=["--x", "something"])
 

tyro/_calling.py

@@ -170,9 +170,15 @@ def get_value_from_arg(prefixed_field_name: str) -> Any:
                     field.name if field.name_override is None else field.name_override
                 ] = value
 
-    unwrapped_f = _resolver.unwrap_origin_strip_extras(f)
-    unwrapped_f = list if unwrapped_f is Sequence else unwrapped_f  # type: ignore
+    # Note: we unwrap types both before and after narrowing. This is because narrowing
+    # sometimes produces types like `Tuple[T1, T2, ...]`, where we actually want just
+    # `tuple`.
+    unwrapped_f = f
+    unwrapped_f = _resolver.unwrap_origin_strip_extras(unwrapped_f)
     unwrapped_f = _resolver.narrow_type(unwrapped_f, default_instance)
+    unwrapped_f = _resolver.unwrap_origin_strip_extras(unwrapped_f)
+    unwrapped_f = list if unwrapped_f is Sequence else unwrapped_f  # type: ignore
+
     if unwrapped_f in (tuple, list, set):
         if len(args) == 0:
             # When tuples are used as nested structures (eg Tuple[SomeDataclass]), we

tyro/_resolver.py

@@ -2,6 +2,7 @@
 import collections.abc
 import copy
 import dataclasses
+import pathlib
 import sys
 from typing import (
     Any,
@@ -118,8 +119,21 @@ def narrow_type(typ: TypeT, default_instance: Any) -> TypeT:
     should parse as Cat.
 
     Note that Union types are intentionally excluded here."""
+
+    # Don't apply narrowing for pathlib.PosixPath, pathlib.WindowsPath, etc.
+    # This is mostly an aesthetic decision, and is needed because pathlib.Path() hacks
+    # __new__ to dynamically choose between path types.
+    if typ is pathlib.Path:
+        return typ
+
     try:
         potential_subclass = type(default_instance)
+
+        if potential_subclass is type:
+            # Don't narrow to `type`. This happens when the default instance is a class;
+            # it doesn't really make sense to parse this case.
+            return typ
+
         superclass = unwrap_annotated(typ)[0]
         if superclass is Any or issubclass(potential_subclass, superclass):  # type: ignore
             if get_origin(typ) is Annotated: