Added support for default_factory.

datargs/compat/__init__.py

@@ -70,8 +70,17 @@ def has_default(self) -> bool:
 
     @property
     def default(self):
+        if self._field.default is not dataclasses.MISSING:
+            return self._field.default
+        if self._field.default_factory is not dataclasses.MISSING:
+            return self._field.default_factory()
+        # in this case, normally None will be returned
         return self._field.default
 
+    @property
+    def default_factory(self):
+        return self._field.default_factory
+
     @property
     def name(self):
         return self._field.name
@@ -98,7 +107,8 @@ class DataField(RecordField[dataclasses.Field]):
     """
 
     def is_required(self) -> bool:
-        return self.default is dataclasses.MISSING
+        return self.default is dataclasses.MISSING and \
+            self.default_factory is dataclasses.MISSING
 
 
 class NotARecordClass(Exception):

datargs/make.py

@@ -42,6 +42,7 @@
 Specifying enums by name is not currently supported.
 """
 import dataclasses
+import argparse
 
 # noinspection PyUnresolvedReferences,PyProtectedMember
 from argparse import (
@@ -288,19 +289,26 @@ def literal_arg(name: str, field: RecordField, override: dict) -> Action:
         field, {**override, "choices": choices, "type": inner_type}
     )
 
+class NegateAction(argparse.Action):
+    def __call__(self, parser, namespace, values, option_string=None):
+        setattr(namespace, self.dest, option_string[2:4] != 'no')
+
 
 @TypeDispatch.register(bool)
 def bool_arg(name: str, field: RecordField, override: dict) -> Action:
     kwargs = {
         **subdict(common_kwargs(field), ["type"]),
         **override,
-        "action": "store_false"
-        if field.default and field.has_default()
-        else "store_true",
+        "action": NegateAction,
+        "nargs": 0, # required for NegateAction
+        "default": field.default if field.has_default() else None,
     }
     kwargs.pop("type", None)
+
+    negate_name = f"--no-{name[2:]}"
+    args = [*get_option_strings(name, field), negate_name]
     return Action(
-        args=get_option_strings(name, field),
+        args=args,
         kwargs=kwargs,
     )
 
@@ -478,7 +486,8 @@ def parse(cls: Type[T], args: Optional[Sequence[str]] = None, *, parser=None) ->
     >>> parse(Args, ["--num", "1"])
     Args(is_flag=False, num=1)
     """
-    result = vars(make_parser(cls, parser=parser).parse_args(args))
+    parser = make_parser(cls, parser=parser)
+    result = vars(parser.parse_args(args))
     try:
         command_dest = cls.__datargs_params__.sub_commands.get("dest", None)
     except AttributeError:

tests/test_arg_type.py

@@ -1,7 +1,7 @@
 from abc import ABC
 import sys
 from argparse import ArgumentParser
-from dataclasses import dataclass
+from dataclasses import dataclass, field
 from enum import Enum
 from pathlib import Path
 from typing import Type, Sequence, Text, NoReturn, TypeVar, Optional
@@ -79,12 +79,12 @@ class TestStoreTrueNoDefault:
 
     @factory
     class TestStoreFalse:
-        store_false: bool = True
+        default_true: bool = True
 
     args = parse_test(TestStoreFalse, [])
-    assert args.store_false
-    args = parse_test(TestStoreFalse, ["--store-false"])
-    assert not args.store_false
+    assert args.default_true
+    args = parse_test(TestStoreFalse, ["--no-default-true"])
+    assert not args.default_true
 
 
 def test_str(factory):
@@ -360,6 +360,19 @@ class Nargs:
     args = parse_test(Nargs, [])
     assert args.nums == []
 
+def test_default_factory_dataclass():
+    class UserClass:
+        def __init__(self, value=1):
+            self.value = value
+    @dataclass()
+    class DefaultFactory:
+        user_class: UserClass = field(default_factory=UserClass)
+
+    args = parse_test(DefaultFactory, ["--user-class", "2"])
+    assert args.user_class.value == "2"
+    args = parse_test(DefaultFactory, [])
+    assert args.user_class.value == 1
+
 
 is_pre_38 = sys.version_info < (3, 8)