new_contents: # encoding: utf-8
  
  import re
  from mongoengine import connect
  
  from marrow.package.loader import load
  from web.core.compat import native, iteritems
  
  
  log = __import__('logging').getLogger(__name__)
  
  _safe_uri_replace = re.compile(r'(\w+)://(\w+):(?P<password>[^@]+)@')
  
  
  class MongoEngineExtension:
  	__slots__ = ('uri', 'db', 'connection', 'cb')
  	
  	provides = ['db']
  	
  	def __init__(self, uri, **config):
  		self.uri = uri
  		
  		log.info("Connecting MongoEngine to '%s'.", _safe_uri_replace.sub(r'\1://\2@', uri))
  		
  		connection = self.connection = dict(tz_aware=True)
  		
  		scheme, parts = uri.split('://', 1)
  		parts, self.db = parts.split('/', 1)
  		auth, host = parts.split('@', 1) if '@' in parts else (None, parts)
  		
  		if scheme != 'mongo':
  			raise Exception('The URL must begin with \'mongo://\'!')
  		
  		connection['host'], connection['port'] = host.split(':') if ':' in host else (host, '27017')
  		connection['port'] = int(connection['port'])
  		
  		if auth:  # pragma: no cover
  			connection['username'], _, connection['password'] = auth.partition(':')
  		
  		# Accept additional keyword arguments to mongoengine.connect() from the INI.
  		for k, v in iteritems(config):
  			pfx, _, k = k.rpartition('.')
  			if pfx != prefix or k in ('alias', 'engine', 'model', 'ready'): continue
  			connection[k] = int(v) if v.isdigit() else v
  		
  		self.cb = config.get('ready', None)
  	
  	def start(self, context):
  		db, connection = self.db, self.connection
  		log.debug("Connecting to %s database with connection information: %r", db, connection)
  		
  		context.mongoengine = connect(db, **connection)
  		
  		cb = self.cb
  		if cb is not None:
  			cb = load(cb) if isinstance(cb, native) else cb
  			
  			if hasattr(cb, '__call__'):
  				cb()
  
subject: Add MongoEngine to the pile.