Make BoolArg nullable (still a bit untested)

Author: MatejVitek

src/matej/argparse.py

@@ -131,6 +131,8 @@ def __init__(self, *flags, **kw):
 		"""
 		self.flags = flags
 		self.kw = kw
+		if 'nargs' in kw and (kw['nargs'] in ('*', '+') or isinstance(kw['nargs'], int) and kw['nargs'] > 1):
+			self.kw.setdefault('default', [])
 
 	def add_to_ap(self, parser, **kw):
 		""" Add this argument to the given parser. """
@@ -236,16 +238,14 @@ class PathArg(NullableArg, type=Path):
 	""" Path argument. """
 
 
-class BoolArg(Arg):
+class BoolArg(NullableArg):
 	""" Boolean argument. """
-	def __init__(self, *flags, default=False, negative_flags=None, help="", negative_help=None, **kw):
+	def __init__(self, *flags, negative_flags=None, help="", negative_help=None, **kw):
 		"""
 		Initialise the argument.
 
 		Parameters
 		----------
-		default : bool, default=False
-			Default value for the argument.
 		negative_flags : Collection[str], optional
 			Flags that set the argument to `False`. By default, they will be automatically generated by prefixing the long flags with `--no-`˙.
 			If `...` is passed inside the `negative_flags` list, the auto-generated flags will be included in the list at that position.
@@ -260,7 +260,7 @@ def __init__(self, *flags, default=False, negative_flags=None, help="", negative
 		For other parameters, see the documentation of :meth:`Arg.__init__`.
 		"""
 		super().__init__(*flags, **kw)
-		self.default = default
+		self.default = self.kw.pop('default', False)
 
 		self.short_flags = [flag for flag in self.flags if flag[0] == '-' and flag[1] != '-']
 		self.yes_flags = [flag for flag in self.flags if flag[:2] == '--']
@@ -277,9 +277,9 @@ def __init__(self, *flags, default=False, negative_flags=None, help="", negative
 		self.short_help = help + " (this toggles the default if no value is passed)" if help else help
 		self.yes_help = help
 		self.no_help = negative_help if negative_help is not None else "Do not " + help[0].lower() + help[1:] if help else help
-		if default:
+		if self.default is True:
 			self.yes_help += " <default>"
-		else:
+		elif self.default is False:
 			self.no_help += " <default>"
 
 	def add_to_ap(self, parser, **kw):
@@ -296,23 +296,25 @@ def add_to_ap(self, parser, **kw):
 		  - toggle the default value if no argument is passed.
 		"""
 		kw = self.kw | kw
+		typeless_kw = {k: v for k, v in kw.items() if k != 'type'}  # Need this for yes and no flags, since type conflicts with store_x actions
 		dest = kw.get('dest', (self.yes_flags[0] if self.yes_flags else self.flags[0]).lstrip('-')).replace('-', '_')
 		group = parser.add_mutually_exclusive_group()
 		result = None
 		if self.yes_flags:
-			result = group.add_argument(*self.yes_flags, dest=dest, default=argparse.SUPPRESS, action='store_true', help=self.yes_help, **kw)
+			result = group.add_argument(*self.yes_flags, dest=dest, default=argparse.SUPPRESS, action='store_true', help=self.yes_help, **typeless_kw)
 		if self.no_flags:
-			group.add_argument(*self.no_flags, dest=dest, default=argparse.SUPPRESS, action='store_false', help=self.no_help, **kw)
+			group.add_argument(*self.no_flags, dest=dest, default=argparse.SUPPRESS, action='store_false', help=self.no_help, **typeless_kw)
 		if self.short_flags:
-			result = group.add_argument(*self.short_flags, dest=dest, nargs='?', default=self.default, const=not self.default, type=self._str_to_bool, help=self.short_help, **kw)
+			result = group.add_argument(*self.short_flags, dest=dest, nargs='?', default=bool(self.default), const=not self.default, help=self.short_help, **kw)
 		return result
 
 	@staticmethod
 	def _no_f(arg):
 		return '--no-' + arg.lstrip('-')
 
-	@staticmethod
-	def _str_to_bool(s):
+	def _type(self, s):
+		if super()._type(s) is None:
+			return None
 		return s.lower() in ('true', 'yes', 't', 'y', '1')