--- a/configuration/config.py	Tue Mar 27 13:00:14 2012 -0700
+++ b/configuration/config.py	Tue Mar 27 14:01:25 2012 -0700
@@ -88,6 +88,9 @@
 
     configuration_providers.append(YAML())
 
+# TODO: add a configuration provider for taking command-line arguments
+# from a file
+
 __all__.extend([i.__class__.__name__ for i in configuration_providers])
 
 ### optparse interface
@@ -269,9 +272,8 @@
     def parser(self, configuration_provider_option=None, dump='--dump', **parser_args):
         """
         return OptionParser for this Configuration instance
-        - configuration_provider_options : option for configuration files [TODO]
-        (also TODO: a special value that equates to the first file extension value
-        for the configuration_providers)
+        - configuration_provider_options : option for configuration files
+          (or '-' for taking from the extensions names)
         - dump : option for dumping configuration
         - parser_args : arguments to the OptionParser constructor
         """
@@ -292,7 +294,24 @@
         parser.parsed = set()
         self.optparse_options(parser)
 
-        # TODO: add option(s) for configuration_providers
+        # add option(s) for configuration_providers
+        if configuration_provider_option:
+            if configuration_provider_option == '-':
+                raise NotImplementedError("""
+The arguments will be interspersed.  Will need to be more clever to get this
+to work properly.
+""")
+
+                # take option from configuration_provider extensions
+                for format in self.formats():
+                    parser.add_option('--%s' % format,
+                                      dest='load_%s' % format,
+                                      action='append',
+                                      help="load configuration from a %s file" % format)
+            else:
+                parser.add_option(configuration_provider_option,
+                                  dest='load', action='append',
+                                  help="load configuration from a file")
 
         # add an option for dumping
         formats = self.formats()
@@ -303,7 +322,11 @@
         return parser
 
     def parse(self, args=sys.argv[1:], parser=None, configuration_provider_option=None):
-        """parse configuration including command line options"""
+        """
+        parse configuration including command line options
+        - args: command line arguments to parse (default: system arguments)
+        - parser
+        """
 
         # parse arguments
         if parser is None:
@@ -319,6 +342,15 @@
             cli_config = dict([(key, value) for key, value in cli_config.items()
                                if key in parser.parsed])
 
+        # deserialize configuration
+        configuration_files = getattr(options, 'load', [])
+        missing = [i for i in configuration_files
+                   if not os.path.exists(i)]
+        if missing:
+            parser.error("Missing files: %s" % ', '.join(missing))
+        for f in configuration_files:
+            pass
+
         # generate configuration
         self(cli_config)
 
@@ -378,6 +410,8 @@
         """load configuration from a file"""
         # TODO: allow file object vs file name
 
+        assert os.path.exists(filename)
+
         # get the format
         if not format:
             format = self.filename2format(filename)