evtmgr.py

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#---------------------------------------------------------------------------
# Name:        wxPython.lib.evtmgr
# Purpose:     An easier, more "Pythonic" and more OO method of registering
#              handlers for wxWindows events using the Publish/Subscribe
#              pattern.
#
# Author:      Robb Shecter and Robin Dunn
#
# Created:     12-December-2002
# RCS-ID:      $Id: evtmgr.py,v 1.9 2005/06/02 03:41:32 RD Exp $
# Copyright:   (c) 2003 by db-X Corporation
# Licence:     wxWindows license
#---------------------------------------------------------------------------
# 12/02/2003 - Jeff Grimmett ([e-mail])
#
# o Updated for 2.5 compatability.
#

"""
A module that allows multiple handlers to respond to single wxWidgets
events.  This allows true NxN Observer/Observable connections: One
event can be received by multiple handlers, and one handler can
receive multiple events.

There are two ways to register event handlers.  The first way is
similar to standard wxPython handler registration::

    from wx.lib.evtmgr import eventManager
    eventManager.Register(handleEvents, EVT_BUTTON, win=frame, id=101)

There's also a new object-oriented way to register for events.  This
invocation is equivalent to the one above, but does not require the
programmer to declare or track control ids or parent containers::

    eventManager.Register(handleEvents, EVT_BUTTON, myButton)

This module is Python 2.1+ compatible.

"""
import  wx
import  pubsub # publish / subscribe library

#---------------------------------------------------------------------------


class EventManager:
    """
    This is the main class in the module, and is the only class that
    the application programmer needs to use.  There is a pre-created
    instance of this class called 'eventManager'.  It should not be
    necessary to create other instances.
    """
    def __init__(self):
        self.eventAdapterDict    = {}
        self.messageAdapterDict  = {}
        self.windowTopicLookup   = {}
        self.listenerTopicLookup = {}
        self.__publisher         = pubsub.Publisher()
        self.EMPTY_LIST          = []


    def Register(self, listener, event, source=None, win=None, id=None):
        """
        Registers a listener function (or any callable object) to
        receive events of type event coming from the source window.
        For example::
        
            eventManager.Register(self.OnButton, EVT_BUTTON, theButton)

        Alternatively, the specific window where the event is
        delivered, and/or the ID of the event source can be specified.
        For example::
        
            eventManager.Register(self.OnButton, EVT_BUTTON, win=self, id=ID_BUTTON)
            
        or::
        
            eventManager.Register(self.OnButton, EVT_BUTTON, theButton, self)
            
        """

        # 1. Check if the 'event' is actually one of the multi-
        #    event macros.
        if _macroInfo.isMultiEvent(event):
            raise 'Cannot register the macro, '+`event`+'.  Register instead the individual events.'

        # Support a more OO API.  This allows the GUI widget itself to
        # be specified, and the id to be retrieved from the system,
        # instead of kept track of explicitly by the programmer.
        # (Being used to doing GUI work with Java, this seems to me to be
        # the natural way of doing things.)
        if source is not None:
            id  = source.GetId()
            
        if win is None:
            # Some widgets do not function as their own windows.
            win = self._determineWindow(source)
            
        topic = (event, win, id)

        #  Create an adapter from the PS system back to wxEvents, and
        #  possibly one from wxEvents:
        if not self.__haveMessageAdapter(listener, topic):
            messageAdapter = MessageAdapter(eventHandler=listener, topicPattern=topic)
            try:
                self.messageAdapterDict[topic][listener] = messageAdapter
            except KeyError:
                self.messageAdapterDict[topic] = {}
                self.messageAdapterDict[topic][listener] = messageAdapter

            if not self.eventAdapterDict.has_key(topic):
                self.eventAdapterDict[topic] = EventAdapter(event, win, id)
        else:
            # Throwing away a duplicate request
            pass

        # For time efficiency when deregistering by window:
        try:
            self.windowTopicLookup[win].append(topic)
        except KeyError:
            self.windowTopicLookup[win] = []
            self.windowTopicLookup[win].append(topic)

        # For time efficiency when deregistering by listener:
        try:
            self.listenerTopicLookup[listener].append(topic)
        except KeyError:
            self.listenerTopicLookup[listener] = []
            self.listenerTopicLookup[listener].append(topic)

        # See if the source understands the listeningFor protocol.
        # This is a bit of a test I'm working on - it allows classes
        # to know when their events are being listened to.  I use
        # it to enable chaining events from contained windows only
        # when needed.
        if source is not None:
            try:
                # Let the source know that we're listening  for this
                # event.
                source.listeningFor(event)
            except AttributeError:
                pass

    # Some aliases for Register, just for kicks
    Bind = Register
    Subscribe = Register


    def DeregisterWindow(self, win):
        """
        Deregister all events coming from the given window.
        """
        win    = self._determineWindow(win)
        topics = self.__getTopics(win)

        if topics:
            for aTopic in topics:
                self.__deregisterTopic(aTopic)

            del self.windowTopicLookup[win]


    def DeregisterListener(self, listener):
        """
        Deregister all event notifications for the given listener.
        """
        try:
            topicList = self.listenerTopicLookup[listener]
        except KeyError:
            return

        for topic in topicList:
            topicDict = self.messageAdapterDict[topic]

            if topicDict.has_key(listener):
                topicDict[listener].Destroy()
                del topicDict[listener]

                if len(topicDict) == 0:
                    self.eventAdapterDict[topic].Destroy()
                    del self.eventAdapterDict[topic]
                    del self.messageAdapterDict[topic]

        del self.listenerTopicLookup[listener]


    def GetStats(self):
        """
        Return a dictionary with data about my state.
        """
        stats = {}
        stats['Adapters: Message'] = reduce(lambda x,y: x+y, [0] + map(len, self.messageAdapterDict.values()))
        stats['Adapters: Event']   = len(self.eventAdapterDict)
        stats['Topics: Total']     = len(self.__getTopics())
        stats['Topics: Dead']      = len(self.GetDeadTopics())
        return stats


    def DeregisterDeadTopics(self):
        """
        Deregister any entries relating to dead
        wxPython objects.  Not sure if this is an
        important issue; 1) My app code always de-registers
        listeners it doesn't need.  2) I don't think
        that lingering references to these dead objects
        is a problem.
        """
        for topic in self.GetDeadTopics():
            self.__deregisterTopic(topic)


    def GetDeadTopics(self):
        """
        Return a list of topics relating to dead wxPython
        objects.
        """
        return filter(self.__isDeadTopic, self.__getTopics())


    def __winString(self, aWin):
        """
        A string rep of a window for debugging
        """
        try:
            name = aWin.GetClassName()
            i    = id(aWin)
            return '%s #%d' % (name, i)
        except wx.PyDeadObjectError:
            return '(dead wx.Object)'


    def __topicString(self, aTopic):
        """
        A string rep of a topic for debugging
        """
        return '[%-26s %s]' % (aTopic[0].__name__, self.winString(aTopic[1]))


    def __listenerString(self, aListener):
        """
        A string rep of a listener for debugging
        """
        try:
            return aListener.im_class.__name__ + '.' + aListener.__name__
        except:
            return 'Function ' + aListener.__name__


    def __deregisterTopic(self, aTopic):
        try:
            messageAdapterList = self.messageAdapterDict[aTopic].values()
        except KeyError:
            # This topic isn't valid.  Probably because it was deleted
            # by listener.
            return

        for messageAdapter in messageAdapterList:
            messageAdapter.Destroy()

        self.eventAdapterDict[aTopic].Destroy()
        del self.messageAdapterDict[aTopic]
        del self.eventAdapterDict[aTopic]


    def __getTopics(self, win=None):
        if win is None:
            return self.messageAdapterDict.keys()