'Parameters:
* ``pattern``: Regular expression to be matched. Any capturing
groups in the regex will be passed in to the handler\'s
get/post/etc methods as arguments (by keyword if named, by
position if unnamed. Named and unnamed capturing groups may
may not be mixed in the same rule).
* ``handler``: `~.web.RequestHandler` subclass to be invoked.
* ``kwargs`` (optional): A dictionary of additional arguments
to be passed to the handler\'s constructor.
* ``name`` (optional): A name for this handler.  Used by
`~.web.Application.reverse_url`.'

def __init__(self, pattern, handler, kwargs=None, name=None):

    super(URLSpec, self).__init__(PathMatches(pattern), handler, kwargs, name)
    self.regex = self.matcher.regex
    self.handler_class = self.target
    self.kwargs = kwargs
