fix postponed annotation when field is overwritten (#228)

Author: mixilchenko

simple_parsing/annotation_utils/get_field_annotations.py

@@ -5,6 +5,7 @@
 import typing
 from contextlib import contextmanager
 from dataclasses import InitVar
+from itertools import dropwhile
 from logging import getLogger as get_logger
 from typing import Any, Dict, Iterator, Optional, get_type_hints
 
@@ -190,13 +191,14 @@ def get_field_type_from_annotations(some_class: type, field_name: str) -> type:
     if frame is not None:
         local_ns.update(frame.f_locals)
 
-    # Get the global_ns in the module starting from the deepest base until the module where the field_name is defined.
+    # Get the global_ns in the module starting from the deepest base until the module with the field_name last definition.
     global_ns = {}
-    for base_cls in reversed(some_class.mro()):
+    classes_to_iterate = list(dropwhile(
+        lambda cls: field_name not in getattr(cls, "__annotations__", {}),
+        some_class.mro()
+    ))
+    for base_cls in reversed(classes_to_iterate):
         global_ns.update(sys.modules[base_cls.__module__].__dict__)
-        annotations = getattr(base_cls, "__annotations__", None)
-        if annotations and field_name in annotations:
-            break
 
     try:
         with _initvar_patcher():

test/postponed_annotations/overwrite_attribute.py

@@ -0,0 +1,16 @@
+from __future__ import annotations
+
+from dataclasses import dataclass
+
+from ..test_utils import TestSetup
+from .overwrite_base import Base, ParamCls
+
+
+@dataclass
+class ParamClsSubclass(ParamCls):
+    v: bool
+
+
+@dataclass
+class Subclass(Base, TestSetup):
+    attribute: ParamClsSubclass

test/postponed_annotations/overwrite_base.py

@@ -4,10 +4,10 @@
 
 
 @dataclass
-class Foo:
+class ParamCls:
     ...
 
 
 @dataclass
 class Base:
-    a: Foo
+    attribute: ParamCls

test/postponed_annotations/overwrite_subclass.py

@@ -7,10 +7,10 @@
 
 
 @dataclass
-class Foo:
+class ParamCls:
     something_else: bool = True
 
 
 @dataclass
 class Subclass(Base, TestSetup):
-    other_attribute: Foo
+    other_attribute: ParamCls

test/postponed_annotations/test_postponed_annotations.py

@@ -57,11 +57,27 @@ def test_postponed_annotations_with_multi_depth_inherits_2():
 
 
 def test_overwrite_base():
+    """Test that postponed annotations don't break types with the same name in multiple files."""
     import test.postponed_annotations.overwrite_base as overwrite_base
     import test.postponed_annotations.overwrite_subclass as overwrite_subclass
 
     assert overwrite_subclass.Subclass.setup(
         "--something_else False"
     ) == overwrite_subclass.Subclass(
-        a=overwrite_base.Foo(), other_attribute=overwrite_subclass.Foo(False)
+        attribute=overwrite_base.ParamCls(),
+        other_attribute=overwrite_subclass.ParamCls(False),
     )
+
+
+def test_overwrite_field():
+    """Test that postponed annotations don't break attribute overwriting in multiple files."""
+    import test.postponed_annotations.overwrite_base as overwrite_base
+    import test.postponed_annotations.overwrite_attribute as overwrite_attribute
+
+    instance = overwrite_attribute.Subclass.setup("--v True")
+    assert type(instance.attribute) != overwrite_base.ParamCls, (
+        "attribute type from Base class correctly ignored"
+    )
+    assert instance == overwrite_attribute.Subclass(
+        attribute=overwrite_attribute.ParamClsSubclass(True)
+    ), "parsed attribute value is correct"