Re: Channels -- a question about how ProtocolTypeRouter works

I would instead think of the object that ends up there as a factory that makes the final objects that end up per-scope. It's slightly confusing, I will grant you, but in Python anything can make a new class instance, not just a class constructor, which is what's happening here.

Andrew

On Fri, Oct 26, 2018 at 3:17 PM Zhiyu (Drew) Li <zyli2004@gmail.com> wrote:

Thanks!  So that means some objects last across multiple scopes, and they can create another obj that only lasts for one specific scope?

I am still confused how the different layers of middleware wrap around the real asgi application -- a obj just lasts for one scope. 

I need to go through the code deeper.  

Thanks

Drew

On Fri, Oct 26, 2018 at 4:07 PM Andrew Godwin <andrew@aeracode.org> wrote:

Hi Drew,

The return value is indeed an object, but if you look closely at it you'll see it defines a __call__ method - meaning that when it's called as an ASGI application, it then returns a further object to act inside the scope.

Andrew

On Fri, Oct 26, 2018 at 2:55 PM Zhiyu/Drew Li <zyli2004@gmail.com> wrote:

Hi,    Newbie here. (please bear with me if this a stupid question)

I am going through the tutorial and doc and got this question regarding how ProtocolTypeRouter works.  ProtocolTypeRouter.__init__ takes a dict "application_mapping" and append a key-value pair to it: "http': class AsgiHandler  As doc says ASGI application is created on a per scope basis, I think I vaguely understand how the "http" one works.   Once a http scope comes in, an instance/object of class AsgiHandler is initiated, which lasts for the duration of the scope.  So it is one scope leads to one ASGI application/object    But I am confused about this one:  application = ProtocolTypeRouter({      # (http->django views is added by default)      'websocket': AuthMiddlewareStack(          URLRouter(              chat.routing.websocket_urlpatterns          )      ),  })  The whole value of this key-value pair AuthMiddlewareStack(URLRouter(chat.routing.websocket_urlpatterns)) seems to be a object not a class,   so that means the application already exists before a websocket scope comes in. How does this conform to "one scope one application" rule?    Any help would be appreciated.    Thanks  Drew

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