update help of "add" command, and improve code

weboob/applications/weboobcfg/weboobcfg.py

@@ -93,25 +93,24 @@ class WeboobCfg(ReplApplication):
 
     def do_add(self, line):
         """
-        add NAME [OPTIONS ...]
+        add MODULE_NAME [BACKEND_NAME] [PARAMETERS ...]
 
-        Add a backend.
+        Create a backend from a module. By default, if BACKEND_NAME is omitted,
+        that's the module name which is used.
+
+        You can specify parameters from command line in form "key=value".
         """
         if not line:
             print('You must specify a module name. Hint: use the "modules" command.', file=self.stderr)
             return 2
+
         module_name, options = self.parse_command_args(line, 2, 1)
         if options:
             options = options.split(' ')
         else:
             options = ()
 
-        backend_name = module_name
+        backend_name = None
-        try:
-            k, v = options[0].split('=',1)
-        except ValueError:
-            backend_name = options[0]
-            del options[0]
 
         params = {}
         # set backend params from command-line arguments
@@ -119,11 +118,15 @@ class WeboobCfg(ReplApplication):
             try:
                 key, value = option.split('=', 1)
             except ValueError:
-                print('Parameters have to be formatted "key=value"', file=self.stderr)
+                if backend_name is None:
-                return 2
+                    backend_name = option
-            params[key] = value
+                else:
+                    print('Parameters have to be formatted "key=value"', file=self.stderr)
+                    return 2
+            else:
+                params[key] = value
 
-        self.add_backend(module_name, backend_name, params)
+        self.add_backend(module_name, backend_name or module_name, params)
 
     def do_register(self, line):
         """