python borg pattern singleton

borg.py

"""
Singleton class encapsulating a psycopg2 connection.
"""
import psycopg2
from psycopg2.extras import DictCursor

psycopg2.extensions.register_type(psycopg2.extensions.UNICODE)
psycopg2.extensions.register_type(psycopg2.extensions.UNICODEARRAY)

class DB(object):
    """Borg pattern singleton"""
    __state = {}
    def __init__(self):
        self.__dict__ = self.__state
        if not hasattr(self, 'conn'):
            self.conn = psycopg2.connect(database='foo',
                                         user='bar',
                                         host='baz')
            self.cur = self.conn.cursor(cursor_factory=DictCursor)
            
if __name__ == '__main__':
  db = DB()
  db.cur.execute("some sql here")