Thuban/Lib/connector.py

# This module was copied almost verbatim from Sketch. The only change is
# the base class of ConnectorError which was a Sketch specific exception
# class. 

# Sketch - A Python-based interactive drawing program
# Copyright (C) 1997, 1998, 2000, 2001, 2003 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

__version__ = "$Revision$"

#
#       The Connector
#

import sys
from types import MethodType

from Thuban import _

class ConnectorError(Exception):
    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
        # Iterate over a copy of receivers because the receivers might
        # unsubscribe themselves when receiving a message and Disconnect
        # would modify receivers in place while we're iterating over it.
        for func, fargs in receivers[:]:
            try:
                apply(func, args + fargs)
            except:
                sys.stderr.write(_("Warning: %s.%s: %s%s\n")
                                 % (object, channel, func, fargs))
                import traceback
                traceback.print_exc()

    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 hex(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:

    # Flag indicating whether the publisher instance was destroyed.
    _was_destroyed = False

    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):
        """Unsubscribe from the channel.

        If the publisher's Destroy method has been called already, do
        nothing, because the subscriptions will already have been
        removed in Destroy and trying to disconnect it here will lead to
        exceptions.
        """
        if not self._was_destroyed:
            Disconnect(self, channel, func, args)

    def issue(self, channel, *args):
        apply(Issue, (self, channel,) + args)

    def Destroy(self):
        """Remove all subscriptions of messages sent by self."""
        RemovePublisher(self)
        self._was_destroyed = True


class Conduit(Publisher):

    def _do_forward(self, *args, **kw):
        self.issue(args[-1], *args[:-1], **kw)

    def subscribe_forwarding(self, channel, obj):
        if obj is not None:
            obj.Subscribe(channel, self._do_forward, channel)

    def unsubscribe_forwarding(self, channel, obj):
        if obj is not None:
            obj.Unsubscribe(channel, self._do_forward, channel)

1	bh	6	# This module was copied almost verbatim from Sketch. The only change is
2			# the base class of ConnectorError which was a Sketch specific exception
3			# class.
4
5			# Sketch - A Python-based interactive drawing program
6	bh	1144	# Copyright (C) 1997, 1998, 2000, 2001, 2003 by Bernhard Herzog
7	bh	6	#
8			# This library is free software; you can redistribute it and/or
9			# modify it under the terms of the GNU Library General Public
10			# License as published by the Free Software Foundation; either
11			# version 2 of the License, or (at your option) any later version.
12			#
13			# This library is distributed in the hope that it will be useful,
14			# but WITHOUT ANY WARRANTY; without even the implied warranty of
15			# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
16			# Library General Public License for more details.
17			#
18			# You should have received a copy of the GNU Library General Public
19			# License along with this library; if not, write to the Free Software
20			# Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
21
22			__version__ = "$Revision$"
23
24			#
25			# The Connector
26			#
27
28			import sys
29			from types import MethodType
30
31	jan	374	from Thuban import _
32
33	bh	6	class ConnectorError(Exception):
34			pass
35
36			class Connector:
37
38			def __init__(self):
39			self.connections = {}
40
41			def Connect(self, object, channel, function, args):
42			idx = id(object)
43			if self.connections.has_key(idx):
44			channels = self.connections[idx]
45			else:
46			channels = self.connections[idx] = {}
47
48			if channels.has_key(channel):
49			receivers = channels[channel]
50			else:
51			receivers = channels[channel] = []
52
53			info = (function, args)
54			try:
55			receivers.remove(info)
56			except ValueError:
57			pass
58			receivers.append(info)
59
60			def Disconnect(self, object, channel, function, args):
61			try:
62			receivers = self.connections[id(object)][channel]
63			except KeyError:
64			raise ConnectorError, \
65	jan	374	_('no receivers for channel %s of %s') % (channel, object)
66	bh	6	try:
67			receivers.remove((function, args))
68			except ValueError:
69			raise ConnectorError,\
70	jan	374	_('receiver %s%s is not connected to channel %s of %s') \
71	bh	6	% (function, args, channel, object)
72
73			if not receivers:
74			# the list of receivers is empty now, remove the channel
75			channels = self.connections[id(object)]
76			del channels[channel]
77			if not channels:
78			# the object has no more channels
79			del self.connections[id(object)]
80
81			def Issue(self, object, channel, *args):
82			#print object, channel, args
83			try:
84			receivers = self.connections[id(object)][channel]
85			except KeyError:
86			return
87	bh	1144	# Iterate over a copy of receivers because the receivers might
88			# unsubscribe themselves when receiving a message and Disconnect
89			# would modify receivers in place while we're iterating over it.
90			for func, fargs in receivers[:]:
91	bh	6	try:
92			apply(func, args + fargs)
93			except:
94	jan	374	sys.stderr.write(_("Warning: %s.%s: %s%s\n")
95	bh	6	% (object, channel, func, fargs))
96			import traceback
97			traceback.print_exc()
98
99			def RemovePublisher(self, object):
100			i = id(object)
101			if self.connections.has_key(i):
102			del self.connections[i]
103			# don't use try: del ... ; except KeyError here. That would create a
104			# new reference of object in a traceback object and this method should
105			# be callable from a __del__ method (at least for versions prior
106			# Python 1.5)
107
108			def HasSubscribers(self, object):
109			return self.connections.has_key(id(object))
110
111			def print_connections(self):
112			# for debugging
113			for id, channels in self.connections.items():
114			for name, subscribers in channels.items():
115	bh	62	print hex(id), name
116	bh	6	for func, args in subscribers:
117			if type(func) == MethodType:
118	jan	374	print _('\tmethod %s of %s') % (func.im_func.func_name,
119			func.im_self)
120	bh	6	else:
121			print '\t', func
122
123
124
125			_the_connector = Connector()
126
127			Connect = _the_connector.Connect
128			Issue = _the_connector.Issue
129			RemovePublisher = _the_connector.RemovePublisher
130			Disconnect = _the_connector.Disconnect
131			def Subscribe(channel, function, *args):
132			return Connect(None, channel, function, args)
133
134
135			class Publisher:
136
137	bh	1952	# Flag indicating whether the publisher instance was destroyed.
138			_was_destroyed = False
139
140	bh	6	def __del__(self):
141			# the new finalization code in 1.5.1 might bind RemovePublisher
142			# to None before all objects derived from Publisher are deleted...
143			if RemovePublisher is not None:
144			RemovePublisher(self)
145
146			def Subscribe(self, channel, func, *args):
147			Connect(self, channel, func, args)
148
149			def Unsubscribe(self, channel, func, *args):
150	bh	1952	"""Unsubscribe from the channel.
151	bh	6
152	bh	1952	If the publisher's Destroy method has been called already, do
153			nothing, because the subscriptions will already have been
154			removed in Destroy and trying to disconnect it here will lead to
155			exceptions.
156			"""
157			if not self._was_destroyed:
158			Disconnect(self, channel, func, args)
159
160	bh	6	def issue(self, channel, *args):
161			apply(Issue, (self, channel,) + args)
162
163			def Destroy(self):
164	bh	1952	"""Remove all subscriptions of messages sent by self."""
165	bh	6	RemovePublisher(self)
166	bh	1952	self._was_destroyed = True
167	bh	1778
168
169			class Conduit(Publisher):
170
171			def _do_forward(self, args, *kw):
172			self.issue(args[-1], args[:-1], *kw)
173
174			def subscribe_forwarding(self, channel, obj):
175			if obj is not None:
176			obj.Subscribe(channel, self._do_forward, channel)
177
178			def unsubscribe_forwarding(self, channel, obj):
179			if obj is not None:
180			obj.Unsubscribe(channel, self._do_forward, channel)
181
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