twisted.spread.pb.ViewPoint : API documentation

I act as an indirect reference to an object accessed through a pb.IPerspective.

Simply put, I combine an object with a perspective so that when a peer calls methods on the object I refer to, the method will be invoked with that perspective as a first argument, so that it can know who is calling it.

While Viewable objects will be converted to ViewPoints by default when they are returned from or sent as arguments to a remote method, any object may be manually proxied as well. (XXX: Now that this class is no longer named Proxy, this is the only occurrence of the term 'proxied' in this docstring, and may be unclear.)

This can be useful when dealing with pb.IPerspectives, Copyables, and Cacheables. It is legal to implement a method as such on a perspective:

 | def perspective_getViewPointForOther(self, name):
 |     defr = self.service.getPerspectiveRequest(name)
 |     defr.addCallbacks(lambda x, self=self: ViewPoint(self, x), log.msg)
 |     return defr

This will allow you to have references to Perspective objects in two different ways. One is through the initial 'attach' call -- each peer will have a pb.RemoteReference to their perspective directly. The other is through this method; each peer can get a pb.RemoteReference to all other perspectives in the service; but that pb.RemoteReference will be to a ViewPoint, not directly to the object.

The practical offshoot of this is that you can implement 2 varieties of remotely callable methods on this Perspective; view_xxx and perspective_xxx. view_xxx methods will follow the rules for ViewPoint methods (see ViewPoint.remoteMessageReceived), and perspective_xxx methods will follow the rules for Perspective methods.

def __init__(self, perspective, object): (source)

Initialize me with a Perspective and an Object.

perspective = (source)

overrides twisted.spread.pb.Referenceable.perspective

I am an object sent remotely as a direct reference.

When one of my subclasses is sent as an argument to or returned from a remote method call, I will be serialized by default as a direct reference.

This means that the peer will be able to call methods on me; a method call xxx() from my peer will be resolved to methods of the name remote_xxx.

object = (source)

Undocumented

def processUniqueID(self): (source)

overrides twisted.spread.pb.Serializable.processUniqueID

Return an ID unique to a proxy for this perspective+object combination.

def remoteMessageReceived(self, broker, message, args, kw): (source)

overrides twisted.spread.pb.Referenceable.remoteMessageReceived

A remote message has been received. Dispatch it appropriately.

The default implementation is to dispatch to a method called 'view_messagename' to my Object and call it on my object with the same arguments, modified by inserting my Perspective as the first argument.

Method	__init__	Initialize me with a Perspective and an Object.
Instance Variable	perspective	I am an object sent remotely as a direct reference.
Instance Variable	object	Undocumented
Method	processUniqueID	Return an ID unique to a proxy for this perspective+object combination.
Method	remoteMessageReceived	A remote message has been received. Dispatch it appropriately.