Added method TaggedEC2Object.remove_tags()

Pull Request #2259 already created an add_tags method to supplement the add_tag
call. Not sure why there isn't an analogous remove_tags method, since the
DeleteTags API also supports removng multiple tags at once. An immediate use
case is to be able to delete all the tags of an instance; with only remove_tag,
this will unnecessarily involve many round trips to AWS.

1 files changed, 30 insertions, 7 deletions

diff --git a/boto/ec2/ec2object.py b/boto/ec2/ec2object.py
index 9edf12ee..7cc7e424 100644
--- a/boto/ec2/ec2object.py
+++ b/boto/ec2/ec2object.py
@@ -65,7 +65,7 @@ class TaggedEC2Object(EC2Object):
 
     def add_tag(self, key, value='', dry_run=False):
         """
-        Add a tag to this object.  Tag's are stored by AWS and can be used
+        Add a tag to this object.  Tags are stored by AWS and can be used
         to organize and filter resources.  Adding a tag involves a round-trip
         to the EC2 service.
 
@@ -117,12 +117,12 @@ class TaggedEC2Object(EC2Object):
 
         :type value: str
         :param value: An optional value that can be stored with the tag.
-                      If a value is provided, it must match the value
-                      currently stored in EC2.  If not, the tag will not
-                      be removed.  If a value of None is provided, all
-                      tags with the specified name will be deleted.
-                      NOTE: There is an important distinction between
-                      a value of '' and a value of None.
+                      If a value is provided, it must match the value currently
+                      stored in EC2.  If not, the tag will not be removed.  If
+                      a value of None is provided, the tag will be
+                      unconditionally deleted.
+                      NOTE: There is an important distinction between a value
+                      of '' and a value of None.
         """
         if value is not None:
             tags = {key: value}
@@ -135,3 +135,26 @@ class TaggedEC2Object(EC2Object):
         )
         if key in self.tags:
             del self.tags[key]
+
+    def remove_tags(self, tags, dry_run=False):
+        """
+        Removes tags from this object.  Removing tags involves a round-trip
+        to the EC2 service.
+
+        :type tags: dict
+        :param tags: A dictionary of key-value pairs for the tags being removed.
+                     For each key, the provided value must match the value
+                     currently stored in EC2.  If not, that particular tag will
+                     not be removed.  However, if a value of None is provided,
+                     the tag will be unconditionally deleted.
+                     NOTE: There is an important distinction between a value of
+                     '' and a value of None.
+        """
+        status = self.connection.delete_tags(
+            [self.id],
+            tags,
+            dry_run=dry_run
+        )
+        for key, value in tags.iteritems():
+            if key in self.tags:
+                del self.tags[key]