steps toward support for adding tags

Author: dwhswenson

paths_cli/commands/append.py

@@ -16,8 +16,13 @@
 @MULTI_NETWORK.clicked(required=False)
 @MULTI_SCHEME.clicked(required=False)
 @MULTI_TAG.clicked(required=False)
+@click.option('--save-tag', type=str, default=None,
+              help=("save object to a tag; requires that only one "
+                    + "object be specfied. Can also be used to rename "
+                    + "tagged objects. To append a tagged object without "
+                    + "a tag, use --add-tag \"\""))
 def append(input_file, append_file, engine, cv, volume, network, scheme,
-           tag):
+           tag, save_tag):
     """Append objects from INPUT_FILE to another file.
     """
     storage = INPUT_FILE.get(input_file)
@@ -29,9 +34,26 @@ def append(input_file, append_file, engine, cv, volume, network, scheme,
     for arg, param in zip(args, params):
         to_save.extend(param.get(storage, arg))
 
+    to_save = [obj for obj in to_save if obj is not None]
+    if save_tag is not None and len(to_save) != 1:
+        raise RuntimeError("Can't identify the object to tag when saving "
+                           + str(len(to_save)) + " objects.")
+
     for obj in to_save:
         output_storage.save(obj)
 
+    if tag and save_tag is None:
+        save_tag = tag
+
+    if save_tag:
+        output_storage.tags[save_tag] = to_save[0]
+
+    # TO TEST
+    # 1. append a tag in a new file: its tag comes with it
+    # 2. rename a tagged object
+    # 3. "untag" an object by not associating a tag in the new storage
+    # 4. tag a previously untagged object
+
     output_storage.close()