Deferred events

userevent.py

from collections import namedtuple
from twisted.internet.defer import Deferred

UserEvent = namedtuple("UserEvent", "subject, args, kwargs")


class UserEventStack(object):
        
    def __init__(self, user):
        self.events = []
        self.user = user
        self.d = None
    
    def __len__(self):
        return len(self.events)
        
    def __iter__(self):
        return self.events.__iter__()
        
    def onEvent(self, subject, *args, **kwargs):
        """
        Entry point for producers
        """
        
        self.tell(subject, *args, **kwargs)
        if self.d and self.d.called != True:
            self.d.callback(self)

    def tell(self, subject, *args, **kwargs):
        """
            Shortcut for direct event injection
        """
        self.events.append(UserEvent(subject, args, kwargs))
    
    def getAll(self):
        """
            Not exactly perfect but at point of call grabs all "events"
            and empties the event stack
        """
        events, self.events = self.events[:], []
        return events
    
    def check(self):
        """
            Call point for consumers
        """
        if self.d is None:
            self.d = Deferred()
        elif self.d.called == True:
            self.d = Deferred()
            
        if self.events:
            self.d.callback(self)
        
        return self.d
    
    def reset(self):
        self.d.cancel()
        self.d = Deferred()