quantum源碼分析22

class Controller(object):
    """WSGI app that dispatched to methods.
     與Method對應的controller，上面說到，一個路由表會指定一個controller。

    WSGI app that reads routing information supplied by RoutesMiddleware
    and calls the requested action method upon itself.  All action methods
    must, in addition to their normal parameters, accept a 'req' argument
    which is the incoming wsgi.Request.  They raise a webob.exc exception,
    or return a dict which will be serialized by requested content type.
    """
    #裝飾爲一個WSGI應用
    @webob.dec.wsgify(RequestClass=Request)
    def __call__(self, req):
        """
        Call the method specified in req.environ by RoutesMiddleware.
        """
        arg_dict = req.environ['wsgiorg.routing_args'][1]
        action = arg_dict['action']
        method = getattr(self, action)
        del arg_dict['controller']
        del arg_dict['action']
        if 'format' in arg_dict:
            del arg_dict['format']
        arg_dict['request'] = req
        #執行方法，這裏是一個抽象，子類繼承後決定具體怎麼執行  
        result = method(**arg_dict)