Refactor the parser and remove caveman's testing

argclass.py

@@ -1,6 +1,6 @@
 import typing
 from argparse import ArgumentParser
-from dataclasses import dataclass, field, MISSING
+from dataclasses import dataclass, MISSING
 
 
 def make_gnu_option(name):
@@ -55,7 +55,12 @@ def _prepare_list_cfg(name, field_):
         **decide_default(field_),
         **get_choices(field_),
     }
-    arg_cfg['type'] = typing.get_args(field_.type)[0]
+    subtype = typing.get_args(field_.type)
+    if not subtype:
+        arg_cfg['type'] = str
+    else:
+        arg_cfg['type'] = subtype[0]
+
     if field_.metadata.get('allow_empty', False):
         arg_cfg['nargs'] = '*'
     else:
@@ -87,7 +92,7 @@ def _prepare_trivial(ap: ArgumentParser, name, field_):
 def prepare_field(ap, name, field_):
     if field_.type is bool:
         _prepare_bool(ap, name, field_)
-    elif typing.get_origin(field_.type) is list:
+    elif field_.type is list or typing.get_origin(field_.type) is list:
         _prepare_list(ap, name, field_)
     else:
         _prepare_trivial(ap, name, field_)
@@ -95,29 +100,13 @@ def prepare_field(ap, name, field_):
 
 def argclass(cls):
 
-    class ArgClass(dataclass(cls)):
-
     @classmethod
-        def parse_args(cls):
+    def parse_args(cls, argv):
         ap = ArgumentParser()
         for name, field_ in cls.__dataclass_fields__.items():
             prepare_field(ap, name, field_)
-            return ap.parse_args()
+        return cls(**vars(ap.parse_args(argv)))
 
-    return ArgClass
-
-
-@argclass
-class A:
-    required_int_arg: int
-    required_bool_arg: bool
-    required_int_arg_with_choices: int = field(metadata={'choices': [3, 4, 5]})
-    arg_with_default: str = 'abc'
-    list_arg_with_default: list[int] = field(default_factory=lambda: [1, 2])
-    list_arg_with_default_mb_empty: list[int] = field(
-        default_factory=lambda: [], metadata={'allow_empty': True}
-    )
-
-
-if __name__ == '__main__':
-    print(A.parse_args())
+    cls = dataclass(cls)
+    cls.parse_args = parse_args
+    return cls