Add support for parsers that can be used bare, no required args.

voussoirkit/betterhelp.py

@@ -3,6 +3,18 @@ import functools
 
 HELPSTRINGS = {'', 'help', '-h', '--help'}
 
+def can_use_bare(parser):
+    has_func = bool(parser.get_default('func'))
+    has_required_args = any(action.required for action in parser._actions)
+    return has_func and not has_required_args
+
+def can_use_bare_subparsers(subparser_action):
+    can_bares = set(
+        sp_name for (sp_name, sp) in subparser_action.choices.items()
+        if can_use_bare(sp)
+    )
+    return can_bares
+
 def docstring_preview(text):
     '''
     This function assumes that your docstring is formatted with a single blank
@@ -49,12 +61,15 @@ def betterhelp(parser, docstring):
     lesser of two evils. Plus, maybe someday I'll find a need for it and won't
     have to make any changes to do it.
     '''
+    can_bare = can_use_bare(parser)
     def wrapper(main):
         @functools.wraps(main)
         def wrapped(argv):
             argument = listget(argv, 0, '').lower()
 
-            if argument in HELPSTRINGS:
+            if argument == '' and can_bare:
+                pass
+            elif argument in HELPSTRINGS:
                 print(docstring)
                 return 1
 
@@ -68,7 +83,6 @@ def get_subparser_action(parser):
             return action
     raise TypeError('Couldn\'t locate the SubParsersAction.')
 
-
 def set_alias_docstrings(sub_docstrings, subparser_action):
     '''
     When using subparser aliases:
@@ -102,22 +116,31 @@ def set_alias_docstrings(sub_docstrings, subparser_action):
 def subparser_betterhelp(parser, main_docstring, sub_docstrings):
     subparser_action = get_subparser_action(parser)
     sub_docstrings = set_alias_docstrings(sub_docstrings, subparser_action)
+    can_bare = can_use_bare(parser)
+    can_bares = can_use_bare_subparsers(subparser_action)
 
     def wrapper(main):
         @functools.wraps(main)
         def wrapped(argv):
             command = listget(argv, 0, '').lower()
 
+            if command == '' and can_bare:
+                return main(argv)
+
             if command not in sub_docstrings:
                 print(main_docstring)
                 if command == '':
-                    print('You are seeing the default help text because you did not choose a command.')
+                    because = 'you did not choose a command.'
+                    print(f'You are seeing the default help text because {because}')
                 elif command not in HELPSTRINGS:
-                    print(f'You are seeing the default help text because "{command}" was not recognized')
+                    because = f'"{command}" was not recognized'
+                    print(f'You are seeing the default help text because {because}')
                 return 1
 
             argument = listget(argv, 1, '').lower()
-            if argument in HELPSTRINGS:
+            if argument == '' and command in can_bares:
+                pass
+            elif argument in HELPSTRINGS:
                 print(sub_docstrings[command])
                 return 1