report inability to signal --existing kernels

IPython/frontend/zmqterminal/app.py

@@ -1,120 +1,124 b''
 """ A minimal application using the ZMQ-based terminal IPython frontend.
 
 This is not a complete console app, as subprocess will not be able to receive
 input, there is no real readline support, among other limitations.
 
 Authors:
 
 * Min RK
 * Paul Ivanov
 
 """
 
 #-----------------------------------------------------------------------------
 # Imports
 #-----------------------------------------------------------------------------
 import signal
 import sys
 import time
 
 from IPython.frontend.terminal.ipapp import TerminalIPythonApp
 
 from IPython.utils.traitlets import (
     Dict, List, Unicode, Int, CaselessStrEnum, CBool, Any
 )
 from IPython.zmq.ipkernel import IPKernelApp
 from IPython.zmq.session import Session, default_secure
 from IPython.zmq.zmqshell import ZMQInteractiveShell
 from IPython.frontend.kernelmixinapp import (
         IPythonMixinConsoleApp, app_aliases, app_flags
     )
 
 from IPython.frontend.zmqterminal.interactiveshell import ZMQTerminalInteractiveShell
 
 #-----------------------------------------------------------------------------
 # Globals
 #-----------------------------------------------------------------------------
 
 _examples = """
 ipython console # start the ZMQ-based console
 ipython console --existing # connect to an existing ipython session
 """
 
 #-----------------------------------------------------------------------------
 # Flags and Aliases
 #-----------------------------------------------------------------------------
 
 # XXX: the app_flags should really be flags from the mixin
 flags = dict(app_flags)
 frontend_flags = { }
 flags.update(frontend_flags)
 
 frontend_flags = frontend_flags.keys()
 
 aliases = dict(app_aliases)
 
 frontend_aliases = dict()
 
 aliases.update(frontend_aliases)
 
 #-----------------------------------------------------------------------------
 # Classes
 #-----------------------------------------------------------------------------
 
 
 class ZMQTerminalIPythonApp(TerminalIPythonApp, IPythonMixinConsoleApp):
     name = "ipython console"
     """Start a terminal frontend to the IPython zmq kernel."""
 
     description = """
         The IPython terminal-based Console.
 
         This launches a Console application inside a terminal.
 
         The Console supports various extra features beyond the traditional
         single-process Terminal IPython shell, such as connecting to an
         existing ipython session, via:
 
             ipython console --existing
 
         where the previous session could have been created by another ipython
         console, an ipython qtconsole, or by opening an ipython notebook.
 
     """
     examples = _examples
 
     classes = List([IPKernelApp, ZMQTerminalInteractiveShell])
     flags = Dict(flags)
     aliases = Dict(aliases)
     subcommands = Dict()
     def parse_command_line(self, argv=None):
         super(ZMQTerminalIPythonApp, self).parse_command_line(argv)
         IPythonMixinConsoleApp.parse_command_line(self,argv)
         self.swallow_args(frontend_aliases,frontend_flags,argv=argv)
 
     def init_shell(self):
         IPythonMixinConsoleApp.initialize(self)
         # relay sigint to kernel
         signal.signal(signal.SIGINT, self.handle_sigint)
         self.shell = ZMQTerminalInteractiveShell.instance(config=self.config,
                         display_banner=False, profile_dir=self.profile_dir,
                         ipython_dir=self.ipython_dir, kernel_manager=self.kernel_manager)
 
     def handle_sigint(self, *args):
         self.shell.write('KeyboardInterrupt\n')
-        self.kernel_manager.interrupt_kernel()
+        if self.kernel_manager.has_kernel:
+            self.kernel_manager.interrupt_kernel()
+        else:
+            print 'Kernel process is either remote or unspecified.',
+            print 'Cannot interrupt.'
 
     def init_code(self):
         # no-op in the frontend, code gets run in the backend
         pass
 
 def launch_new_instance():
     """Create and run a full blown IPython instance"""
     app = ZMQTerminalIPythonApp.instance()
     app.initialize()
     app.start()
 
 
 if __name__ == '__main__':
     launch_new_instance()