/boto-2.5.2/boto/ec2/ec2object.py

# Copyright (c) 2006-2010 Mitch Garnaat http://garnaat.org/
# Copyright (c) 2010, Eucalyptus Systems, Inc.
#
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"""
Represents an EC2 Object
"""
from boto.ec2.tag import TagSet

class EC2Object(object):

    def __init__(self, connection=None):
        self.connection = connection
        if self.connection and hasattr(self.connection, 'region'):
            self.region = connection.region
        else:
            self.region = None

    def startElement(self, name, attrs, connection):
        return None

    def endElement(self, name, value, connection):
        setattr(self, name, value)

    
class TaggedEC2Object(EC2Object):
    """
    Any EC2 resource that can be tagged should be represented
    by a Python object that subclasses this class.  This class
    has the mechanism in place to handle the tagSet element in
    the Describe* responses.  If tags are found, it will create
    a TagSet object and allow it to parse and collect the tags
    into a dict that is stored in the "tags" attribute of the
    object.
    """

    def __init__(self, connection=None):
        EC2Object.__init__(self, connection)
        self.tags = TagSet()

    def startElement(self, name, attrs, connection):
        if name == 'tagSet':
            return self.tags
        else:
            return None

    def add_tag(self, key, value=''):
        """
        Add a tag to this object.  Tag's are stored by AWS and can be used
        to organize and filter resources.  Adding a tag involves a round-trip
        to the EC2 service.

        :type key: str
        :param key: The key or name of the tag being stored.

        :type value: str
        :param value: An optional value that can be stored with the tag.
                      If you want only the tag name and no value, the
                      value should be the empty string.
        """
        status = self.connection.create_tags([self.id], {key : value})
        if self.tags is None:
            self.tags = TagSet()
        self.tags[key] = value

    def remove_tag(self, key, value=None):
        """
        Remove a tag from this object.  Removing a tag involves a round-trip
        to the EC2 service.

        :type key: str
        :param key: The key or name of the tag being stored.

        :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 value:
            tags = {key : value}
        else:
            tags = [key]
        status = self.connection.delete_tags([self.id], tags)
        if key in self.tags:
            del self.tags[key]