Improved help string and updated demo

demo.py

@@ -9,9 +9,12 @@ def add_one(num: int) -> int:
 # ----- ArgumentParser -----
 
 parser = ArgumentParser()
-parser.add_argument('--rnn', type=str, required=True)
-parser.add_argument('--hidden_size', type=int, default=300)
-parser.add_argument('--dropout', type=float, default=0.2)
+parser.add_argument('--rnn', type=str, required=True,
+                    help='RNN type')
+parser.add_argument('--hidden_size', type=int, default=300,
+                    help='Hidden size')
+parser.add_argument('--dropout', type=float, default=0.2,
+                    help='Dropout probability')
 
 
 args = parser.parse_args()
@@ -24,9 +27,9 @@ def add_one(num: int) -> int:
 # ----- Tap -----
 
 class MyTap(Tap):
-    rnn: str
-    hidden_size: int = 300
-    dropout: float = 0.2
+    rnn: str  # RNN type
+    hidden_size: int = 300  # Hidden size
+    dropout: float = 0.2  # Dropout probability
 
 
 args = MyTap().parse_args()

tap/tap.py

@@ -74,27 +74,35 @@ def _add_argument(self, *name_or_flags, **kwargs) -> None:
         if hasattr(self, variable):
             kwargs['default'] = kwargs.get('default', getattr(self, variable))
 
+        # Set required if option arg
+        if is_option_arg(*name_or_flags) and variable != 'help':
+            kwargs['required'] = kwargs.get('required', not hasattr(self, variable))
+
+        # Set help if necessary
+        if 'help' not in kwargs:
+            kwargs['help'] = '('
+
+            # Type
+            if variable in self._annotations:
+                kwargs['help'] += type_to_str(self._annotations[variable]) + ', '
+
+            # Required/default
+            if kwargs.get('required', False):
+                kwargs['help'] += 'required'
+            else:
+                kwargs['help'] += f'default={kwargs.get("default", None)}'
+
+            kwargs['help'] += ')'
+
+            # Description
+            if variable in self.class_variables:
+                kwargs['help'] += ' ' + self.class_variables[variable]['comment']
+
         # Set other kwargs where not provided
         if variable in self._annotations:
             # Get type annotation
             var_type = self._annotations[variable]
 
-            # Set required if option arg
-            if is_option_arg(*name_or_flags):
-                kwargs['required'] = kwargs.get('required', not hasattr(self, variable))
-
-            # Set help if necessary
-            if 'help' not in kwargs:
-                # Add type and default
-                kwargs['help'] = '(' + type_to_str(var_type)
-                if 'default' in kwargs:
-                    kwargs['help'] += f', default={kwargs["default"]}'
-                kwargs['help'] += ')'
-
-                # Add description
-                if variable in self.class_variables:
-                    kwargs['help'] += ' ' + self.class_variables[variable]['comment']
-
             # If type is not explicitly provided, set it if it's one of our supported default types
             if 'type' not in kwargs:
                 if var_type not in SUPPORTED_DEFAULT_TYPES: