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# This file has been borrowed from :
#
# Sketch - A Python-based interactive drawing program
# Copyright (C) 1997, 1998 by Bernhard Herzog
#
# This library is free software; you can redistribute it and/or
# modify it under the terms of the GNU Library General Public
# License as published by the Free Software Foundation; either
# version 2 of the License, or (at your option) any later version.
#
# This library is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
# Library General Public License for more details.
#
# You should have received a copy of the GNU Library General Public
# License along with this library; if not, write to the Free Software
# Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
#
# The Connector
#
from types import MethodType
class ConnectorError:
pass
class Connector:
def __init__(self):
self.connections = {}
def Connect(self, object, channel, function, args):
idx = id(object)
if self.connections.has_key(idx):
channels = self.connections[idx]
else:
channels = self.connections[idx] = {}
if channels.has_key(channel):
receivers = channels[channel]
else:
receivers = channels[channel] = []
info = (function, args)
try:
receivers.remove(info)
except ValueError:
pass
receivers.append(info)
def Disconnect(self, object, channel, function, args):
try:
receivers = self.connections[id(object)][channel]
except KeyError:
raise ConnectorError, \
'no receivers for channel %s of %s' % (channel, object)
try:
receivers.remove((function, args))
except ValueError:
raise ConnectorError,\
'receiver %s%s is not connected to channel %s of %s' \
% (function, args, channel, object)
if not receivers:
# the list of receivers is empty now, remove the channel
channels = self.connections[id(object)]
del channels[channel]
if not channels:
# the object has no more channels
del self.connections[id(object)]
def Issue(self, object, channel, *args):
#print object, channel, args
try:
receivers = self.connections[id(object)][channel]
except KeyError:
return
for func, fargs in receivers:
apply(func, args + fargs)
def RemovePublisher(self, object):
i = id(object)
if self.connections.has_key(i):
del self.connections[i]
# don't use try: del ... ; except KeyError here. That would create a
# new reference of object in a traceback object and this method should
# be callable from a __del__ method (at least for versions prior
# Python 1.5)
def HasSubscribers(self, object):
return self.connections.has_key(id(object))
def print_connections(self):
# for debugging
for id, channels in self.connections.items():
for name, subscribers in channels.items():
print id, name
for func, args in subscribers:
if type(func) == MethodType:
print '\tmethod %s of %s' % (func.im_func.func_name,
func.im_self)
else:
print '\t', func
_the_connector = Connector()
Connect = _the_connector.Connect
Issue = _the_connector.Issue
RemovePublisher = _the_connector.RemovePublisher
Disconnect = _the_connector.Disconnect
def Subscribe(channel, function, *args):
return Connect(None, channel, function, args)
class Publisher:
ignore_issue = 0
def __del__(self):
# the new finalization code in 1.5.1 might bind RemovePublisher
# to None before all objects derived from Publisher are deleted...
if RemovePublisher is not None:
RemovePublisher(self)
def Subscribe(self, channel, func, *args):
Connect(self, channel, func, args)
def Unsubscribe(self, channel, func, *args):
Disconnect(self, channel, func, args)
def issue(self, channel, *args):
if not self.ignore_issue:
apply(Issue, (self, channel,) + args)
def Destroy(self):
RemovePublisher(self)
class QueueingPublisher(Publisher):
def __init__(self):
self.clear_message_queue()
def queue_message(self, channel, *args):
# Put message in the queue. If it is already queued put it at
# the end. This is done to make certain that no channel gets
# called twice between two calls to flush_message_queue. If the
# order of channel invocation is important two or more queues
# should be used.
message = (channel, args)
if message not in self.message_queue:
self.message_queue.append(message)
def flush_message_queue(self):
# Issue all queued messages and make the queue empty
#
# Issueing messages might result in new messages being queued.
# This does not happen in sketch yet (Jul 1997) but let's hope
# that we don't get infinite loops here...
while self.message_queue:
queue = self.message_queue
self.message_queue = []
for channel, args in queue:
apply(Issue, (self, channel) + args)
def clear_message_queue(self):
self.message_queue = []
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