Embedding IPython Qt console in a PyQt application

Question

I'd like to embed an IPython qt console widget in a PyQt application I am working on. The code provided below (and adapted from https://stackoverflow.com/a/9796491/1332492) Accomplishes this for IPython v0.12. However, this crashes in IPython v0.13 at the line self.heartbeat.start() with RuntimeError: threads can only be started once. Commenting out this line brings up the widget, but doesn't respond to user input.

Does anyone know how to achieve the equivalent functionality for IPython v0.13?

""" Adapted from https://stackoverflow.com/a/9796491/1332492 """ import os import atexit  from IPython.zmq.ipkernel import IPKernelApp from IPython.lib.kernel import find_connection_file from IPython.frontend.qt.kernelmanager import QtKernelManager from IPython.frontend.qt.console.rich_ipython_widget import RichIPythonWidget from IPython.config.application import catch_config_error from PyQt4 import QtCore   class IPythonLocalKernelApp(IPKernelApp):     DEFAULT_INSTANCE_ARGS = ['']      @catch_config_error     def initialize(self, argv=None):         super(IPythonLocalKernelApp, self).initialize(argv)         self.kernel.eventloop = self.loop_qt4_nonblocking      def loop_qt4_nonblocking(self, kernel):         """Non-blocking version of the ipython qt4 kernel loop"""         kernel.timer = QtCore.QTimer()         kernel.timer.timeout.connect(kernel.do_one_iteration)         kernel.timer.start(1000*kernel._poll_interval)      def start(self, argv=DEFAULT_INSTANCE_ARGS):         """Starts IPython kernel app         argv: arguments passed to kernel         """         self.initialize(argv)         self.heartbeat.start()          if self.poller is not None:             self.poller.start()          self.kernel.start()   class IPythonConsoleQtWidget(RichIPythonWidget):     _connection_file = None      def __init__(self, *args, **kw):         RichIPythonWidget.__init__(self, *args, **kw)         self._existing = True         self._may_close = False         self._confirm_exit = False      def _init_kernel_manager(self):         km = QtKernelManager(connection_file=self._connection_file, config=self.config)         km.load_connection_file()         km.start_channels(hb=self._heartbeat)         self.kernel_manager = km         atexit.register(self.kernel_manager.cleanup_connection_file)      def connect_kernel(self, connection_file, heartbeat=False):         self._heartbeat = heartbeat         if os.path.exists(connection_file):             self._connection_file = connection_file         else:             self._connection_file = find_connection_file(connection_file)          self._init_kernel_manager()   def main(**kwargs):     kernelapp = IPythonLocalKernelApp.instance()     kernelapp.start()      widget = IPythonConsoleQtWidget()     widget.connect_kernel(connection_file=kernelapp.connection_file)     widget.show()      return widget  if __name__ == "__main__":     from PyQt4.QtGui import QApplication     app = QApplication([''])     main()     app.exec_() 

Traceback for v0.13

RuntimeError                              Traceback (most recent call last) /Users/beaumont/terminal.py in <module>()      80     from PyQt4.QtGui import QApplication      81     app = QApplication(['']) ---> 82     main()         global main = <function main at 0x106d0c848>      83     app.exec_()  /Users/beaumont/terminal.py in main(**kwargs={})      69 def main(**kwargs):      70     kernelapp = IPythonLocalKernelApp.instance() ---> 71     kernelapp.start()         kernelapp.start = <bound method IPythonLocalKernelApp.start of     <__main__.IPythonLocalKernelApp object at 0x106d10590>>      72       73     widget = IPythonConsoleQtWidget()  /Users/beaumont/terminal.py in start(self=<__main__.IPythonLocalKernelApp object>, argv=[''])      33         """      34         self.initialize(argv) ---> 35         self.heartbeat.start()         self.heartbeat.start = <bound method Heartbeat.start of <Heartbeat(Thread-1, started daemon 4458577920)>>      36       37         if self.poller is not None:  /opt/local/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/threading.pyc in start(self=<Heartbeat(Thread-1, started daemon 4458577920)>)     487             raise RuntimeError("thread.__init__() not called")     488         if self.__started.is_set(): --> 489             raise RuntimeError("threads can only be started once")         global RuntimeError = undefined     490         if __debug__:     491             self._note("%s.start(): starting thread", self)  RuntimeError: threads can only be started once 

Answer 1

Ok, this code seems to do the trick (i.e. it puts a non-blocking ipython interpreter in a Qt widget, which can be embedded into other widgets). Keywords passed to terminal_widget get added to the namespace of the widget

import atexit  from IPython.zmq.ipkernel import IPKernelApp from IPython.lib.kernel import find_connection_file from IPython.frontend.qt.kernelmanager import QtKernelManager from IPython.frontend.qt.console.rich_ipython_widget import RichIPythonWidget from IPython.utils.traitlets import TraitError from PyQt4 import QtGui, QtCore  def event_loop(kernel):     kernel.timer = QtCore.QTimer()     kernel.timer.timeout.connect(kernel.do_one_iteration)     kernel.timer.start(1000*kernel._poll_interval)  def default_kernel_app():     app = IPKernelApp.instance()     app.initialize(['python', '--pylab=qt'])     app.kernel.eventloop = event_loop     return app  def default_manager(kernel):     connection_file = find_connection_file(kernel.connection_file)     manager = QtKernelManager(connection_file=connection_file)     manager.load_connection_file()     manager.start_channels()     atexit.register(manager.cleanup_connection_file)     return manager  def console_widget(manager):     try: # Ipython v0.13         widget = RichIPythonWidget(gui_completion='droplist')     except TraitError:  # IPython v0.12         widget = RichIPythonWidget(gui_completion=True)     widget.kernel_manager = manager     return widget  def terminal_widget(**kwargs):     kernel_app = default_kernel_app()     manager = default_manager(kernel_app)     widget = console_widget(manager)      #update namespace                                                                kernel_app.shell.user_ns.update(kwargs)      kernel_app.start()     return widget  app = QtGui.QApplication([]) widget = terminal_widget(testing=123) widget.show() app.exec_()