Improve CLI

vdirsyncer/cli.py

@@ -101,6 +101,33 @@ def main():
     _main(env, cfg)
 
 
+def parse_pairs_args(pairs_args, all_pairs):
+    if not pairs_args:
+        pairs_args = list(all_pairs)
+    for pair_and_collection in pairs_args:
+        pair, collection = pair_and_collection, None
+        if '/' in pair:
+            pair, collection = pair.split('/')
+
+        try:
+            a_name, b_name, pair_options, storage_defaults = \
+                all_pairs[pair]
+        except KeyError:
+            cli_logger.critical('Pair not found: {}'.format(pair))
+            cli_logger.critical('These are the pairs found: ')
+            cli_logger.critical(list(all_pairs))
+            sys.exit(1)
+
+        if collection is None:
+            collections = [x.strip() for x in
+                           pair_options.get('collections', '').split(',')]
+        else:
+            collections = [collection]
+
+        for c in collections:
+            yield pair, c
+
+
 def _main(env, file_cfg):
     general, all_pairs, all_storages = file_cfg
     app = argvard.Argvard()
@@ -124,23 +151,20 @@ def _main(env, file_cfg):
 
     @sync_command.main('[pairs...]')
     def sync_main(context, pairs=None):
-        '''Syncronize the given pairs. If no pairs are given, all will be
-        synchronized.'''
-        if pairs is None:
-            pairs = list(all_pairs)
+        '''
+        Syncronize the given pairs. If no pairs are given, all will be
+        synchronized.
+        
+        Examples:
+        `vdirsyncer sync` will sync everything configured.
+        `vdirsyncer sync bob frank` will sync the pairs "bob" and "frank".
+        `vdirsyncer sync bob/first_collection` will sync "first_collection"
+        from the pair "bob".
+        '''
         actions = []
-        for pair_name in pairs:
-            try:
+        for pair_name, collection in parse_pairs_args(pairs, all_pairs):
             a_name, b_name, pair_options, storage_defaults = \
                 all_pairs[pair_name]
-            except KeyError:
-                cli_logger.critical('Pair not found: {}'.format(pair_name))
-                cli_logger.critical('These are the pairs found: ')
-                cli_logger.critical(list(all_pairs))
-                sys.exit(1)
-            collections = pair_options.get('collections', '').split(',')
-            for collection in collections:
-                collection = collection.strip()
             if collection:
                 storage_defaults['collection'] = collection
             config_a = dict(storage_defaults)