Draft of debugging the multiple inheritance problems in km.

* Added __init__ methods to KernelManager classes.
* Played with multiple inheritance between the Qt and non-Qt
  classes.
* But, the prompt doesn't show up for the first line of input???

IPython/frontend/qt/kernelmanager.py

@@ -1,141 +1,150 b''
 """ Defines a KernelManager that provides signals and slots.
 """
 
 # System library imports.
 from PyQt4 import QtCore
 import zmq
 
 # IPython imports.
 from IPython.zmq.kernelmanager import KernelManager, SubSocketChannel, \
     XReqSocketChannel, RepSocketChannel
 from util import MetaQObjectHasTraits
 
-
+# When doing multiple inheritance from QtCore.QObject and other classes
+# the calling of the parent __init__'s is a subtle issue:
+# * QtCore.QObject does not call super so you can't use super and put
+#   QObject first in the inheritance list.
+# * QtCore.QObject.__init__ takes 1 argument, the parent. So if you are going
+#   to use super, any class that comes before QObject must pass it something
+#   reasonable.
 
 class QtSubSocketChannel(SubSocketChannel, QtCore.QObject):
 
     # Emitted when any message is received.
     message_received = QtCore.pyqtSignal(object)
 
     # Emitted when a message of type 'pyout' or 'stdout' is received.
     output_received = QtCore.pyqtSignal(object)
 
     # Emitted when a message of type 'pyerr' or 'stderr' is received.
     error_received = QtCore.pyqtSignal(object)
 
     #---------------------------------------------------------------------------
     # 'object' interface
     #---------------------------------------------------------------------------
     
     def __init__(self, *args, **kw):
         """ Reimplemented to ensure that QtCore.QObject is initialized first.
         """
         QtCore.QObject.__init__(self)
         SubSocketChannel.__init__(self, *args, **kw)
 
     #---------------------------------------------------------------------------
     # 'SubSocketChannel' interface
     #---------------------------------------------------------------------------
     
     def call_handlers(self, msg):
         """ Reimplemented to emit signals instead of making callbacks.
         """
         # Emit the generic signal.
         self.message_received.emit(msg)
         
         # Emit signals for specialized message types.
         msg_type = msg['msg_type']
         if msg_type in ('pyout', 'stdout'):
             self.output_received.emit(msg)
         elif msg_type in ('pyerr', 'stderr'):
             self.error_received.emit(msg)
 
     def flush(self):
         """ Reimplemented to ensure that signals are dispatched immediately.
         """
         super(QtSubSocketChannel, self).flush()
         QtCore.QCoreApplication.instance().processEvents()
 
 
 class QtXReqSocketChannel(XReqSocketChannel, QtCore.QObject):
 
     # Emitted when any message is received.
     message_received = QtCore.pyqtSignal(object)
 
     # Emitted when a reply has been received for the corresponding request type.
     execute_reply = QtCore.pyqtSignal(object)
     complete_reply = QtCore.pyqtSignal(object)
     object_info_reply = QtCore.pyqtSignal(object)
 
     #---------------------------------------------------------------------------
     # 'object' interface
     #---------------------------------------------------------------------------
     
     def __init__(self, *args, **kw):
         """ Reimplemented to ensure that QtCore.QObject is initialized first.
         """
         QtCore.QObject.__init__(self)
         XReqSocketChannel.__init__(self, *args, **kw)
     
     #---------------------------------------------------------------------------
     # 'XReqSocketChannel' interface
     #---------------------------------------------------------------------------
     
     def call_handlers(self, msg):
         """ Reimplemented to emit signals instead of making callbacks.
         """
         # Emit the generic signal.
         self.message_received.emit(msg)
         
         # Emit signals for specialized message types.
         msg_type = msg['msg_type']
         signal = getattr(self, msg_type, None)
         if signal:
             signal.emit(msg)
 
 
 class QtRepSocketChannel(RepSocketChannel, QtCore.QObject):
 
     #---------------------------------------------------------------------------
     # 'object' interface
     #---------------------------------------------------------------------------
     
     def __init__(self, *args, **kw):
         """ Reimplemented to ensure that QtCore.QObject is initialized first.
         """
         QtCore.QObject.__init__(self)
         RepSocketChannel.__init__(self, *args, **kw)
 
-
 class QtKernelManager(KernelManager, QtCore.QObject):
     """ A KernelManager that provides signals and slots.
     """
 
     __metaclass__ = MetaQObjectHasTraits
 
     # Emitted when the kernel manager has started listening.
     started_listening = QtCore.pyqtSignal()
 
     # Emitted when the kernel manager has stopped listening.
     stopped_listening = QtCore.pyqtSignal()
 
     # Use Qt-specific channel classes that emit signals.
     sub_channel_class = QtSubSocketChannel
     xreq_channel_class = QtXReqSocketChannel
     rep_channel_class = QtRepSocketChannel
 
+    def __init__(self, *args, **kw):
+        QtCore.QObject.__init__(self)
+        KernelManager.__init__(self, *args, **kw)
+
     #---------------------------------------------------------------------------
     # 'KernelManager' interface
     #---------------------------------------------------------------------------
     
     def start_channels(self):
         """ Reimplemented to emit signal.
         """
         super(QtKernelManager, self).start_channels()
         self.started_listening.emit()
 
     def stop_channels(self):
         """ Reimplemented to emit signal.
         """ 
         super(QtKernelManager, self).stop_channels()
         self.stopped_listening.emit()

IPython/frontend/qt/util.py

@@ -1,25 +1,27 b''
 """ Defines miscellaneous Qt-related helper classes and functions.
 """
 
 # System library imports.
 from PyQt4 import QtCore
 
 # IPython imports.
 from IPython.utils.traitlets import HasTraits
 
 
 MetaHasTraits = type(HasTraits)
 MetaQObject = type(QtCore.QObject)
 
+# You can switch the order of the parents here.
 class MetaQObjectHasTraits(MetaQObject, MetaHasTraits):
     """ A metaclass that inherits from the metaclasses of both HasTraits and
         QObject. 
 
         Using this metaclass allows a class to inherit from both HasTraits and
         QObject. See QtKernelManager for an example.
     """
-
-    def __init__(cls, name, bases, dct):
-        MetaQObject.__init__(cls, name, bases, dct)
-        MetaHasTraits.__init__(cls, name, bases, dct)
+    # pass
+    # ???You can get rid of this, but only if the order above is MetaQObject, MetaHasTraits
+    # def __init__(cls, name, bases, dct):
+    #     MetaQObject.__init__(cls, name, bases, dct)
+    #     MetaHasTraits.__init__(cls, name, bases, dct)
         

IPython/zmq/kernelmanager.py

@@ -1,528 +1,529 b''
 """Classes to manage the interaction with a running kernel.
 
 Todo
 ====
 
 * Create logger to handle debugging and console messages.
 """
 
 #-----------------------------------------------------------------------------
 #  Copyright (C) 2008-2010  The IPython Development Team
 #
 #  Distributed under the terms of the BSD License.  The full license is in
 #  the file COPYING, distributed as part of this software.
 #-----------------------------------------------------------------------------
 
 #-----------------------------------------------------------------------------
 # Imports
 #-----------------------------------------------------------------------------
 
 # Standard library imports.
 from Queue import Queue, Empty
 from subprocess import Popen
 from threading import Thread
 import time
 
 # System library imports.
 import zmq
 from zmq import POLLIN, POLLOUT, POLLERR
 from zmq.eventloop import ioloop
 
 # Local imports.
 from IPython.utils.traitlets import HasTraits, Any, Instance, Type
 from kernel import launch_kernel
 from session import Session
 
 #-----------------------------------------------------------------------------
 # Constants and exceptions
 #-----------------------------------------------------------------------------
 
 LOCALHOST = '127.0.0.1'
 
 class InvalidPortNumber(Exception):
     pass
 
 #-----------------------------------------------------------------------------
 # ZMQ Socket Channel classes
 #-----------------------------------------------------------------------------
 
 class ZmqSocketChannel(Thread):
     """The base class for the channels that use ZMQ sockets.
     """
     context = None
     session = None
     socket = None
     ioloop = None
     iostate = None
     _address = None
 
     def __init__(self, context, session, address):
         """Create a channel
 
         Parameters
         ----------
         context : zmq.Context
             The ZMQ context to use.
         session : session.Session
             The session to use.
         address : tuple
             Standard (ip, port) tuple that the kernel is listening on.
         """
         super(ZmqSocketChannel, self).__init__()
         self.daemon = True
 
         self.context = context
         self.session = session
         if address[1] == 0:
             raise InvalidPortNumber('The port number for a channel cannot be 0.')
         self._address = address
 
     def stop(self):
         """Stop the channel's activity.
 
         This calls :method:`Thread.join` and returns when the thread
         terminates. :class:`RuntimeError` will be raised if 
         :method:`self.start` is called again.
         """
         self.join()
 
     @property
     def address(self):
         """Get the channel's address as an (ip, port) tuple.
         
         By the default, the address is (localhost, 0), where 0 means a random
         port.
         """
         return self._address
 
     def add_io_state(self, state):
         """Add IO state to the eventloop.
 
         Parameters
         ----------
         state : zmq.POLLIN|zmq.POLLOUT|zmq.POLLERR
             The IO state flag to set.
 
         This is thread safe as it uses the thread safe IOLoop.add_callback.
         """
         def add_io_state_callback():
             if not self.iostate & state:
                 self.iostate = self.iostate | state
                 self.ioloop.update_handler(self.socket, self.iostate)
         self.ioloop.add_callback(add_io_state_callback)
 
     def drop_io_state(self, state):
         """Drop IO state from the eventloop.
 
         Parameters
         ----------
         state : zmq.POLLIN|zmq.POLLOUT|zmq.POLLERR
             The IO state flag to set.
 
         This is thread safe as it uses the thread safe IOLoop.add_callback.
         """
         def drop_io_state_callback():
             if self.iostate & state:
                 self.iostate = self.iostate & (~state)
                 self.ioloop.update_handler(self.socket, self.iostate)
         self.ioloop.add_callback(drop_io_state_callback)
 
 
 class XReqSocketChannel(ZmqSocketChannel):
     """The XREQ channel for issues request/replies to the kernel.
     """
 
     command_queue = None
 
     def __init__(self, context, session, address):
         self.command_queue = Queue()
         super(XReqSocketChannel, self).__init__(context, session, address)
 
     def run(self):
         """The thread's main activity.  Call start() instead."""
         self.socket = self.context.socket(zmq.XREQ)
         self.socket.setsockopt(zmq.IDENTITY, self.session.session)
         self.socket.connect('tcp://%s:%i' % self.address)
         self.ioloop = ioloop.IOLoop()
         self.iostate = POLLERR|POLLIN
         self.ioloop.add_handler(self.socket, self._handle_events, 
                                 self.iostate)
         self.ioloop.start()
 
     def stop(self):
         self.ioloop.stop()
         super(XReqSocketChannel, self).stop()
 
     def call_handlers(self, msg):
         """This method is called in the ioloop thread when a message arrives.
 
         Subclasses should override this method to handle incoming messages.
         It is important to remember that this method is called in the thread
         so that some logic must be done to ensure that the application leve
         handlers are called in the application thread.
         """
         raise NotImplementedError('call_handlers must be defined in a subclass.')
 
     def execute(self, code):
         """Execute code in the kernel.
 
         Parameters
         ----------
         code : str
             A string of Python code.
 
         Returns
         -------
         The msg_id of the message sent.
         """
         # Create class for content/msg creation. Related to, but possibly
         # not in Session.
         content = dict(code=code)
         msg = self.session.msg('execute_request', content)
         self._queue_request(msg)
         return msg['header']['msg_id']
 
     def complete(self, text, line, block=None):
         """Tab complete text, line, block in the kernel's namespace.
 
         Parameters
         ----------
         text : str
             The text to complete.
         line : str
             The full line of text that is the surrounding context for the 
             text to complete.
         block : str
             The full block of code in which the completion is being requested.
 
         Returns
         -------
         The msg_id of the message sent.
 
         """
         content = dict(text=text, line=line)
         msg = self.session.msg('complete_request', content)
         self._queue_request(msg)
         return msg['header']['msg_id']
 
     def object_info(self, oname):
         """Get metadata information about an object.
 
         Parameters
         ----------
         oname : str
             A string specifying the object name.
         
         Returns
         -------
         The msg_id of the message sent.
         """
         print oname
         content = dict(oname=oname)
         msg = self.session.msg('object_info_request', content)
         self._queue_request(msg)
         return msg['header']['msg_id']
 
     def _handle_events(self, socket, events):
         if events & POLLERR:
             self._handle_err()
         if events & POLLOUT:
             self._handle_send()
         if events & POLLIN:
             self._handle_recv()
 
     def _handle_recv(self):
         msg = self.socket.recv_json()
         self.call_handlers(msg)
 
     def _handle_send(self):
         try:
             msg = self.command_queue.get(False)
         except Empty:
             pass
         else:
             self.socket.send_json(msg)
         if self.command_queue.empty():
             self.drop_io_state(POLLOUT)
 
     def _handle_err(self):
         # We don't want to let this go silently, so eventually we should log.
         raise zmq.ZMQError()
 
     def _queue_request(self, msg):
         self.command_queue.put(msg)
         self.add_io_state(POLLOUT)
 
 
 class SubSocketChannel(ZmqSocketChannel):
     """The SUB channel which listens for messages that the kernel publishes.
     """
 
     def __init__(self, context, session, address):
         super(SubSocketChannel, self).__init__(context, session, address)
 
     def run(self):
         """The thread's main activity.  Call start() instead."""
         self.socket = self.context.socket(zmq.SUB)
         self.socket.setsockopt(zmq.SUBSCRIBE,'')
         self.socket.setsockopt(zmq.IDENTITY, self.session.session)
         self.socket.connect('tcp://%s:%i' % self.address)
         self.ioloop = ioloop.IOLoop()
         self.iostate = POLLIN|POLLERR
         self.ioloop.add_handler(self.socket, self._handle_events, 
                                 self.iostate)
         self.ioloop.start()
 
     def stop(self):
         self.ioloop.stop()
         super(SubSocketChannel, self).stop()
 
     def call_handlers(self, msg):
         """This method is called in the ioloop thread when a message arrives.
 
         Subclasses should override this method to handle incoming messages.
         It is important to remember that this method is called in the thread
         so that some logic must be done to ensure that the application leve
         handlers are called in the application thread.
         """
         raise NotImplementedError('call_handlers must be defined in a subclass.')
 
     def flush(self, timeout=1.0):
         """Immediately processes all pending messages on the SUB channel.
 
         This method is thread safe.
 
         Parameters
         ----------
         timeout : float, optional
             The maximum amount of time to spend flushing, in seconds. The
             default is one second.
         """
         # We do the IOLoop callback process twice to ensure that the IOLoop
         # gets to perform at least one full poll.
         stop_time = time.time() + timeout
         for i in xrange(2):
             self._flushed = False
             self.ioloop.add_callback(self._flush)
             while not self._flushed and time.time() < stop_time:
                 time.sleep(0.01)
 
     def _handle_events(self, socket, events):
         # Turn on and off POLLOUT depending on if we have made a request
         if events & POLLERR:
             self._handle_err()
         if events & POLLIN:
             self._handle_recv()
 
     def _handle_err(self):
         # We don't want to let this go silently, so eventually we should log.
         raise zmq.ZMQError()
 
     def _handle_recv(self):
         # Get all of the messages we can
         while True:
             try:
                 msg = self.socket.recv_json(zmq.NOBLOCK)
             except zmq.ZMQError:
                 # Check the errno?
                 # Will this tigger POLLERR?
                 break
             else:
                 self.call_handlers(msg)
 
     def _flush(self):
         """Callback for :method:`self.flush`."""
         self._flushed = True
 
 
 class RepSocketChannel(ZmqSocketChannel):
     """A reply channel to handle raw_input requests that the kernel makes."""
 
     def on_raw_input(self):
         pass
 
 
 #-----------------------------------------------------------------------------
 # Main kernel manager class
 #-----------------------------------------------------------------------------
 
 
 class KernelManager(HasTraits):
     """ Manages a kernel for a frontend.
 
     The SUB channel is for the frontend to receive messages published by the
     kernel.
         
     The REQ channel is for the frontend to make requests of the kernel.
     
     The REP channel is for the kernel to request stdin (raw_input) from the
     frontend.
     """
     # The PyZMQ Context to use for communication with the kernel.
     context = Instance(zmq.Context)
 
     # The Session to use for communication with the kernel.
     session = Instance(Session)
 
     # The classes to use for the various channels.
     xreq_channel_class = Type(XReqSocketChannel)
     sub_channel_class = Type(SubSocketChannel)
     rep_channel_class = Type(RepSocketChannel)
     
     # Protected traits.
     _kernel = Instance(Popen)
     _xreq_address = Any
     _sub_address = Any
     _rep_address = Any
     _xreq_channel = Any
     _sub_channel = Any
     _rep_channel = Any
 
     def __init__(self, xreq_address=None, sub_address=None, rep_address=None,
                  context=None, session=None):
         self._xreq_address = (LOCALHOST, 0) if xreq_address is None else xreq_address
         self._sub_address = (LOCALHOST, 0) if sub_address is None else sub_address
         self._rep_address = (LOCALHOST, 0) if rep_address is None else rep_address
         self.context = zmq.Context() if context is None else context
         self.session = Session() if session is None else session
+        super(KernelManager, self).__init__()
 
     #--------------------------------------------------------------------------
     # Channel management methods:
     #--------------------------------------------------------------------------
 
     def start_channels(self):
         """Starts the channels for this kernel.
 
         This will create the channels if they do not exist and then start
         them. If port numbers of 0 are being used (random ports) then you
         must first call :method:`start_kernel`. If the channels have been
         stopped and you call this, :class:`RuntimeError` will be raised.
         """
         self.xreq_channel.start()
         self.sub_channel.start()
         self.rep_channel.start()
 
     def stop_channels(self):
         """Stops the channels for this kernel.
 
         This stops the channels by joining their threads. If the channels
         were not started, :class:`RuntimeError` will be raised.
         """
         self.xreq_channel.stop()
         self.sub_channel.stop()
         self.rep_channel.stop()
 
     @property
     def channels_running(self):
         """Are all of the channels created and running?"""
         return self.xreq_channel.is_alive() \
             and self.sub_channel.is_alive() \
             and self.rep_channel.is_alive()
 
     #--------------------------------------------------------------------------
     # Kernel process management methods:
     #--------------------------------------------------------------------------
 
     def start_kernel(self):
         """Starts a kernel process and configures the manager to use it.
 
         If random ports (port=0) are being used, this method must be called
         before the channels are created.
         """
         xreq, sub = self.xreq_address, self.sub_address
         if xreq[0] != LOCALHOST or sub[0] != LOCALHOST:
             raise RuntimeError("Can only launch a kernel on localhost."
                                "Make sure that the '*_address' attributes are "
                                "configured properly.")
 
         kernel, xrep, pub = launch_kernel(xrep_port=xreq[1], pub_port=sub[1])
         self._kernel = kernel
         print xrep, pub
         self._xreq_address = (LOCALHOST, xrep)
         self._sub_address = (LOCALHOST, pub)
         # The rep channel is not fully working yet, but its base class makes
         # sure the port is not 0. We set to -1 for now until the rep channel
         # is fully working.
         self._rep_address = (LOCALHOST, -1)
 
     @property
     def has_kernel(self):
         """Returns whether a kernel process has been specified for the kernel
         manager.
 
         A kernel process can be set via 'start_kernel' or 'set_kernel'.
         """
         return self._kernel is not None
 
     def kill_kernel(self):
         """ Kill the running kernel. """
         if self._kernel is not None:
             self._kernel.kill()
             self._kernel = None
         else:
             raise RuntimeError("Cannot kill kernel. No kernel is running!")
 
     def signal_kernel(self, signum):
         """ Sends a signal to the kernel. """
         if self._kernel is not None:
             self._kernel.send_signal(signum)
         else:
             raise RuntimeError("Cannot signal kernel. No kernel is running!")
 
     @property
     def is_alive(self):
         """Is the kernel process still running?"""
         if self._kernel is not None:
             if self._kernel.poll() is None:
                 return True
             else:
                 return False
         else:
             # We didn't start the kernel with this KernelManager so we don't
             # know if it is running. We should use a heartbeat for this case.
             return True
 
     #--------------------------------------------------------------------------
     # Channels used for communication with the kernel:
     #--------------------------------------------------------------------------
 
     @property
     def xreq_channel(self):
         """Get the REQ socket channel object to make requests of the kernel."""
         if self._xreq_channel is None:
             self._xreq_channel = self.xreq_channel_class(self.context, 
                                                          self.session,
                                                          self.xreq_address)
         return self._xreq_channel
 
     @property
     def sub_channel(self):
         """Get the SUB socket channel object."""
         if self._sub_channel is None:
             self._sub_channel = self.sub_channel_class(self.context,
                                                        self.session,
                                                        self.sub_address)
         return self._sub_channel
 
     @property
     def rep_channel(self):
         """Get the REP socket channel object to handle stdin (raw_input)."""
         if self._rep_channel is None:
             self._rep_channel = self.rep_channel_class(self.context, 
                                                        self.session,
                                                        self.rep_address)
         return self._rep_channel
 
     @property
     def xreq_address(self):
         return self._xreq_address
 
     @property
     def sub_address(self):
         return self._sub_address
 
     @property
     def rep_address(self):
         return self._rep_address