Prepend environment variables and config values for subparser support

.gitignore

@@ -45,3 +45,5 @@ docs/_build
 
 # IDEs
 .idea
+
+.eggs/

.travis.yml

@@ -1,15 +1,29 @@
 # Config file for automatic testing at travis-ci.org
 
-language: python
-
-python:
-  - "3.5"
-  - "3.4"
-  - "3.3"
-  - "3.2"
-  - "2.7"
-  - "2.6"
-  - "pypy"
+matrix:
+  include:
+  - dist: xenial  # Needed for Python 3.7
+    python: 3.7
+    language: python
+  - dist: xenial  # Needed for Python 3.6
+    python: 3.6
+    language: python
+  - python: 3.5
+    language: python
+  - python: 3.4
+    language: python
+  - python: 3.3
+    language: python
+  - python: 3.2
+    language: python
+  - python: 2.7
+    language: python
+  - python: 2.6
+    language: python
+  - python: pypy
+    language: python
+  - python: pypy3
+    language: python
 
 # command to install dependencies: 
 install: pip install mock
@@ -18,4 +32,4 @@ install: pip install mock
 script: python setup.py test
 
 # migrate to container-based travis.ci: http://docs.travis-ci.com/user/migrating-from-legacy
-sudo: false
+sudo: false

configargparse.py

@@ -265,22 +265,7 @@ class ArgumentParser(argparse.ArgumentParser):
     environment variables and .ini or .yaml-style config files.
     """
 
-    def __init__(self,
-        add_config_file_help=True,
-        add_env_var_help=True,
-        auto_env_var_prefix=None,
-        default_config_files=[],
-        ignore_unknown_config_file_keys=False,
-        config_file_parser_class=DefaultConfigFileParser,
-        args_for_setting_config_path=[],
-        config_arg_is_required=False,
-        config_arg_help_message="config file path",
-        args_for_writing_out_config_file=[],
-        write_out_config_file_arg_help_message="takes the current command line "
-            "args and writes them out to a config file at the given path, then "
-            "exits",
-        **kwargs
-        ):
+    def __init__(self, *args, **kwargs):
 
         """Supports args of the argparse.ArgumentParser constructor
         as **kwargs, as well as the following additional args.
@@ -331,11 +316,34 @@ def __init__(self,
             write_out_config_file_arg_help_message: The help message to use for
                 the args in args_for_writing_out_config_file.
         """
+        # This is the only way to make positional args (tested in the argparse
+        # main test suite) and keyword arguments work across both Python 2 and
+        # 3. This could be refactored to not need extra local variables.
+        add_config_file_help = kwargs.pop('add_config_file_help', True)
+        add_env_var_help = kwargs.pop('add_env_var_help', True)
+        auto_env_var_prefix = kwargs.pop('auto_env_var_prefix', None)
+        default_config_files = kwargs.pop('default_config_files', [])
+        ignore_unknown_config_file_keys = kwargs.pop(
+            'ignore_unknown_config_file_keys', False)
+        config_file_parser_class = kwargs.pop('config_file_parser_class',
+                                              DefaultConfigFileParser)
+        args_for_setting_config_path = kwargs.pop(
+            'args_for_setting_config_path', [])
+        config_arg_is_required = kwargs.pop('config_arg_is_required', False)
+        config_arg_help_message = kwargs.pop('config_arg_help_message',
+                                             "config file path")
+        args_for_writing_out_config_file = kwargs.pop(
+            'args_for_writing_out_config_file', [])
+        write_out_config_file_arg_help_message = kwargs.pop(
+            'write_out_config_file_arg_help_message', "takes the current "
+            "command line args and writes them out to a config file at the "
+            "given path, then exits")
+
         self._add_config_file_help = add_config_file_help
         self._add_env_var_help = add_env_var_help
         self._auto_env_var_prefix = auto_env_var_prefix
 
-        argparse.ArgumentParser.__init__(self, **kwargs)
+        argparse.ArgumentParser.__init__(self, *args, **kwargs)
 
         # parse the additional args
         if config_file_parser_class is None:
@@ -431,6 +439,7 @@ def parse_known_args(self, args = None, namespace = None,
 
         # add env var settings to the commandline that aren't there already
         env_var_args = []
+        nargs = False
         actions_with_env_var_values = [a for a in self._actions
             if not a.is_positional_arg and a.env_var and a.env_var in env_vars
                 and not already_on_command_line(args, a.option_strings)]
@@ -439,20 +448,23 @@ def parse_known_args(self, args = None, namespace = None,
             value = env_vars[key]
             # Make list-string into list.
             if action.nargs or isinstance(action, argparse._AppendAction):
+                nargs = True
                 element_capture = re.match('\[(.*)\]', value)
                 if element_capture:
                     value = [val.strip() for val in element_capture.group(1).split(',') if val.strip()]
             env_var_args += self.convert_item_to_command_line_arg(
                 action, key, value)
 
-        args = args + env_var_args
+        if nargs:
+            args = args + env_var_args
+        else:
+            args = env_var_args + args
 
         if env_var_args:
             self._source_to_settings[_ENV_VAR_SOURCE_KEY] = OrderedDict(
                 [(a.env_var, (a, env_vars[a.env_var]))
                     for a in actions_with_env_var_values])
 
-
         # before parsing any config files, check if -h was specified.
         supports_help_arg = any(
             a for a in self._actions if isinstance(a, argparse._HelpAction))
@@ -484,6 +496,7 @@ def parse_known_args(self, args = None, namespace = None,
 
             # add each config item to the commandline unless it's there already
             config_args = []
+            nargs = False
             for key, value in config_items.items():
                 if key in known_config_keys:
                     action = known_config_keys[key]
@@ -503,9 +516,14 @@ def parse_known_args(self, args = None, namespace = None,
                     if source_key not in self._source_to_settings:
                         self._source_to_settings[source_key] = OrderedDict()
                     self._source_to_settings[source_key][key] = (action, value)
+                    if (action and action.nargs or
+                        isinstance(action, argparse._AppendAction)):
+                        nargs = True
 
-            args = args + config_args
-
+            if nargs:
+                args = args + config_args
+            else:
+                args = config_args + args
 
         # save default settings for use by print_values()
         default_settings = OrderedDict()

setup.py

@@ -84,7 +84,7 @@ def launch_http_server(directory):
 
 setup(
     name='ConfigArgParse',
-    version="0.14.0",
+    version="0.14.1",
     description='A drop-in replacement for argparse that allows options to '
                 'also be set via config files and/or environment variables.',
     long_description=long_description,

tests/test_configargparse.py

@@ -755,6 +755,14 @@ def test_FormatHelp(self):
             '--flag \s*Flag help text'
         )
 
+    def test_FormatHelpProg(self):
+        self.initParser('format_help_prog')
+        self.assertRegex(self.format_help(), 'usage: format_help_prog .*')
+
+    def test_FormatHelpProgLib(self):
+        parser = argparse.ArgumentParser('format_help_prog')
+        self.assertRegex(parser.format_help(), 'usage: format_help_prog .*')
+
     class CustomClass(object):
         def __init__(self, name):
             self.name = name

tox.ini

@@ -1,5 +1,5 @@
 [tox]
-envlist = py26, py27, py32, py33, py34, py35
+envlist = py26, py27, py32, py33, py34, py35, py36, py37, pypy, pypy3
 # py34   # bug with virtualenv so tox doesn't work?
 
 
@@ -27,5 +27,14 @@ basepython=python3.4
 [testenv:py35]
 basepython=python3.5
 
+[testenv:py36]
+basepython=python3.6
+
+[testenv:py37]
+basepython=python3.7
+
 [testenv:pypy]
 basepython=pypy
+
+[testenv:pypy3]
+basepython=pypy3