raise UsageError for unsupported GUI backends

gives clearer, more concise message without traceback

closes  #3609

IPython/kernel/zmq/eventloops.py

@@ -1,223 +1,224 b''
 # encoding: utf-8
 """Event loop integration for the ZeroMQ-based kernels.
 """
 
 #-----------------------------------------------------------------------------
 #  Copyright (C) 2011  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
 #-----------------------------------------------------------------------------
 
 import sys
 
 # System library imports.
 import zmq
 
 # Local imports.
 from IPython.config.application import Application
 from IPython.utils import io
 
 
 #------------------------------------------------------------------------------
 # Eventloops for integrating the Kernel into different GUIs
 #------------------------------------------------------------------------------
 
 def loop_qt4(kernel):
     """Start a kernel with PyQt4 event loop integration."""
 
     from IPython.external.qt_for_kernel import QtCore
     from IPython.lib.guisupport import get_app_qt4, start_event_loop_qt4
 
     kernel.app = get_app_qt4([" "])
     kernel.app.setQuitOnLastWindowClosed(False)
     kernel.timer = QtCore.QTimer()
     kernel.timer.timeout.connect(kernel.do_one_iteration)
     # Units for the timer are in milliseconds
     kernel.timer.start(1000*kernel._poll_interval)
     start_event_loop_qt4(kernel.app)
 
 
 def loop_wx(kernel):
     """Start a kernel with wx event loop support."""
 
     import wx
     from IPython.lib.guisupport import start_event_loop_wx
 
     doi = kernel.do_one_iteration
      # Wx uses milliseconds
     poll_interval = int(1000*kernel._poll_interval)
 
     # We have to put the wx.Timer in a wx.Frame for it to fire properly.
     # We make the Frame hidden when we create it in the main app below.
     class TimerFrame(wx.Frame):
         def __init__(self, func):
             wx.Frame.__init__(self, None, -1)
             self.timer = wx.Timer(self)
             # Units for the timer are in milliseconds
             self.timer.Start(poll_interval)
             self.Bind(wx.EVT_TIMER, self.on_timer)
             self.func = func
 
         def on_timer(self, event):
             self.func()
 
     # We need a custom wx.App to create our Frame subclass that has the
     # wx.Timer to drive the ZMQ event loop.
     class IPWxApp(wx.App):
         def OnInit(self):
             self.frame = TimerFrame(doi)
             self.frame.Show(False)
             return True
 
     # The redirect=False here makes sure that wx doesn't replace
     # sys.stdout/stderr with its own classes.
     kernel.app = IPWxApp(redirect=False)
 
     # The import of wx on Linux sets the handler for signal.SIGINT
     # to 0.  This is a bug in wx or gtk.  We fix by just setting it
     # back to the Python default.
     import signal
     if not callable(signal.getsignal(signal.SIGINT)):
         signal.signal(signal.SIGINT, signal.default_int_handler)
 
     start_event_loop_wx(kernel.app)
 
 
 def loop_tk(kernel):
     """Start a kernel with the Tk event loop."""
 
     import Tkinter
     doi = kernel.do_one_iteration
     # Tk uses milliseconds
     poll_interval = int(1000*kernel._poll_interval)
     # For Tkinter, we create a Tk object and call its withdraw method.
     class Timer(object):
         def __init__(self, func):
             self.app = Tkinter.Tk()
             self.app.withdraw()
             self.func = func
 
         def on_timer(self):
             self.func()
             self.app.after(poll_interval, self.on_timer)
 
         def start(self):
             self.on_timer()  # Call it once to get things going.
             self.app.mainloop()
 
     kernel.timer = Timer(doi)
     kernel.timer.start()
 
 
 def loop_gtk(kernel):
     """Start the kernel, coordinating with the GTK event loop"""
     from .gui.gtkembed import GTKEmbed
 
     gtk_kernel = GTKEmbed(kernel)
     gtk_kernel.start()
 
 
 def loop_cocoa(kernel):
     """Start the kernel, coordinating with the Cocoa CFRunLoop event loop
     via the matplotlib MacOSX backend.
     """
     import matplotlib
     if matplotlib.__version__ < '1.1.0':
         kernel.log.warn(
         "MacOSX backend in matplotlib %s doesn't have a Timer, "
         "falling back on Tk for CFRunLoop integration.  Note that "
         "even this won't work if Tk is linked against X11 instead of "
         "Cocoa (e.g. EPD).  To use the MacOSX backend in the kernel, "
         "you must use matplotlib >= 1.1.0, or a native libtk."
         )
         return loop_tk(kernel)
     
     from matplotlib.backends.backend_macosx import TimerMac, show
 
     # scale interval for sec->ms
     poll_interval = int(1000*kernel._poll_interval)
 
     real_excepthook = sys.excepthook
     def handle_int(etype, value, tb):
         """don't let KeyboardInterrupts look like crashes"""
         if etype is KeyboardInterrupt:
             io.raw_print("KeyboardInterrupt caught in CFRunLoop")
         else:
             real_excepthook(etype, value, tb)
 
     # add doi() as a Timer to the CFRunLoop
     def doi():
         # restore excepthook during IPython code
         sys.excepthook = real_excepthook
         kernel.do_one_iteration()
         # and back:
         sys.excepthook = handle_int
 
     t = TimerMac(poll_interval)
     t.add_callback(doi)
     t.start()
 
     # but still need a Poller for when there are no active windows,
     # during which time mainloop() returns immediately
     poller = zmq.Poller()
     if kernel.control_stream:
         poller.register(kernel.control_stream.socket, zmq.POLLIN)
     for stream in kernel.shell_streams:
         poller.register(stream.socket, zmq.POLLIN)
 
     while True:
         try:
             # double nested try/except, to properly catch KeyboardInterrupt
             # due to pyzmq Issue #130
             try:
                 # don't let interrupts during mainloop invoke crash_handler:
                 sys.excepthook = handle_int
                 show.mainloop()
                 sys.excepthook = real_excepthook
                 # use poller if mainloop returned (no windows)
                 # scale by extra factor of 10, since it's a real poll
                 poller.poll(10*poll_interval)
                 kernel.do_one_iteration()
             except:
                 raise
         except KeyboardInterrupt:
             # Ctrl-C shouldn't crash the kernel
             io.raw_print("KeyboardInterrupt caught in kernel")
         finally:
             # ensure excepthook is restored
             sys.excepthook = real_excepthook
 
 # mapping of keys to loop functions
 loop_map = {
     'qt' : loop_qt4,
     'qt4': loop_qt4,
     'inline': None,
     'osx': loop_cocoa,
     'wx' : loop_wx,
     'tk' : loop_tk,
     'gtk': loop_gtk,
     None : None,
 }
 
 
 def enable_gui(gui, kernel=None):
     """Enable integration with a given GUI"""
     if gui not in loop_map:
-        raise ValueError("GUI %r not supported" % gui)
+        e = "Invalid GUI request %r, valid ones are:%s" % (gui, loop_map.keys())
+        raise ValueError(e)
     if kernel is None:
         if Application.initialized():
             kernel = getattr(Application.instance(), 'kernel', None)
         if kernel is None:
             raise RuntimeError("You didn't specify a kernel,"
                 " and no IPython Application with a kernel appears to be running."
             )
     loop = loop_map[gui]
     if loop and kernel.eventloop is not None and kernel.eventloop is not loop:
             raise RuntimeError("Cannot activate multiple GUI eventloops")
     kernel.eventloop = loop

IPython/kernel/zmq/zmqshell.py

@@ -1,597 +1,602 b''
 """A ZMQ-based subclass of InteractiveShell.
 
 This code is meant to ease the refactoring of the base InteractiveShell into
 something with a cleaner architecture for 2-process use, without actually
 breaking InteractiveShell itself.  So we're doing something a bit ugly, where
 we subclass and override what we want to fix.  Once this is working well, we
 can go back to the base class and refactor the code for a cleaner inheritance
 implementation that doesn't rely on so much monkeypatching.
 
 But this lets us maintain a fully working IPython as we develop the new
 machinery.  This should thus be thought of as scaffolding.
 """
 #-----------------------------------------------------------------------------
 # Imports
 #-----------------------------------------------------------------------------
 from __future__ import print_function
 
 # Stdlib
 import os
 import sys
 import time
 
 # System library imports
 from zmq.eventloop import ioloop
 
 # Our own
 from IPython.core.interactiveshell import (
     InteractiveShell, InteractiveShellABC
 )
 from IPython.core import page
 from IPython.core.autocall import ZMQExitAutocall
 from IPython.core.displaypub import DisplayPublisher
 from IPython.core.error import UsageError
 from IPython.core.magics import MacroToEdit, CodeMagics
 from IPython.core.magic import magics_class, line_magic, Magics
 from IPython.core.payloadpage import install_payload_page
 from IPython.display import display, Javascript
 from IPython.kernel.inprocess.socket import SocketABC
 from IPython.kernel import (
     get_connection_file, get_connection_info, connect_qtconsole
 )
 from IPython.testing.skipdoctest import skip_doctest
 from IPython.utils import openpy
 from IPython.utils.jsonutil import json_clean, encode_images
 from IPython.utils.process import arg_split
 from IPython.utils import py3compat
 from IPython.utils.traitlets import Instance, Type, Dict, CBool, CBytes
 from IPython.utils.warn import error
 from IPython.kernel.zmq.displayhook import ZMQShellDisplayHook
 from IPython.kernel.zmq.datapub import ZMQDataPublisher
 from IPython.kernel.zmq.session import extract_header
 from session import Session
 
 #-----------------------------------------------------------------------------
 # Functions and classes
 #-----------------------------------------------------------------------------
 
 class ZMQDisplayPublisher(DisplayPublisher):
     """A display publisher that publishes data using a ZeroMQ PUB socket."""
 
     session = Instance(Session)
     pub_socket = Instance(SocketABC)
     parent_header = Dict({})
     topic = CBytes(b'displaypub')
 
     def set_parent(self, parent):
         """Set the parent for outbound messages."""
         self.parent_header = extract_header(parent)
     
     def _flush_streams(self):
         """flush IO Streams prior to display"""
         sys.stdout.flush()
         sys.stderr.flush()
 
     def publish(self, source, data, metadata=None):
         self._flush_streams()
         if metadata is None:
             metadata = {}
         self._validate_data(source, data, metadata)
         content = {}
         content['source'] = source
         content['data'] = encode_images(data)
         content['metadata'] = metadata
         self.session.send(
             self.pub_socket, u'display_data', json_clean(content),
             parent=self.parent_header, ident=self.topic,
         )
 
     def clear_output(self, stdout=True, stderr=True, other=True):
         content = dict(stdout=stdout, stderr=stderr, other=other)
         
         if stdout:
             print('\r', file=sys.stdout, end='')
         if stderr:
             print('\r', file=sys.stderr, end='')
         
         self._flush_streams()
         
         self.session.send(
             self.pub_socket, u'clear_output', content,
             parent=self.parent_header, ident=self.topic,
         )
 
 @magics_class
 class KernelMagics(Magics):
     #------------------------------------------------------------------------
     # Magic overrides
     #------------------------------------------------------------------------
     # Once the base class stops inheriting from magic, this code needs to be
     # moved into a separate machinery as well.  For now, at least isolate here
     # the magics which this class needs to implement differently from the base
     # class, or that are unique to it.
 
     @line_magic
     def doctest_mode(self, parameter_s=''):
         """Toggle doctest mode on and off.
 
         This mode is intended to make IPython behave as much as possible like a
         plain Python shell, from the perspective of how its prompts, exceptions
         and output look.  This makes it easy to copy and paste parts of a
         session into doctests.  It does so by:
 
         - Changing the prompts to the classic ``>>>`` ones.
         - Changing the exception reporting mode to 'Plain'.
         - Disabling pretty-printing of output.
 
         Note that IPython also supports the pasting of code snippets that have
         leading '>>>' and '...' prompts in them.  This means that you can paste
         doctests from files or docstrings (even if they have leading
         whitespace), and the code will execute correctly.  You can then use
         '%history -t' to see the translated history; this will give you the
         input after removal of all the leading prompts and whitespace, which
         can be pasted back into an editor.
 
         With these features, you can switch into this mode easily whenever you
         need to do testing and changes to doctests, without having to leave
         your existing IPython session.
         """
 
         from IPython.utils.ipstruct import Struct
 
         # Shorthands
         shell = self.shell
         disp_formatter = self.shell.display_formatter
         ptformatter = disp_formatter.formatters['text/plain']
         # dstore is a data store kept in the instance metadata bag to track any
         # changes we make, so we can undo them later.
         dstore = shell.meta.setdefault('doctest_mode', Struct())
         save_dstore = dstore.setdefault
 
         # save a few values we'll need to recover later
         mode = save_dstore('mode', False)
         save_dstore('rc_pprint', ptformatter.pprint)
         save_dstore('rc_active_types',disp_formatter.active_types)
         save_dstore('xmode', shell.InteractiveTB.mode)
 
         if mode == False:
             # turn on
             ptformatter.pprint = False
             disp_formatter.active_types = ['text/plain']
             shell.magic('xmode Plain')
         else:
             # turn off
             ptformatter.pprint = dstore.rc_pprint
             disp_formatter.active_types = dstore.rc_active_types
             shell.magic("xmode " + dstore.xmode)
 
         # Store new mode and inform on console
         dstore.mode = bool(1-int(mode))
         mode_label = ['OFF','ON'][dstore.mode]
         print('Doctest mode is:', mode_label)
 
         # Send the payload back so that clients can modify their prompt display
         payload = dict(
             source='IPython.kernel.zmq.zmqshell.ZMQInteractiveShell.doctest_mode',
             mode=dstore.mode)
         shell.payload_manager.write_payload(payload)
         
     
     _find_edit_target = CodeMagics._find_edit_target
 
     @skip_doctest
     @line_magic
     def edit(self, parameter_s='', last_call=['','']):
         """Bring up an editor and execute the resulting code.
 
         Usage:
           %edit [options] [args]
 
         %edit runs an external text editor. You will need to set the command for
         this editor via the ``TerminalInteractiveShell.editor`` option in your
         configuration file before it will work.
 
         This command allows you to conveniently edit multi-line code right in
         your IPython session.
 
         If called without arguments, %edit opens up an empty editor with a
         temporary file and will execute the contents of this file when you
         close it (don't forget to save it!).
 
 
         Options:
 
         -n <number>: open the editor at a specified line number.  By default,
         the IPython editor hook uses the unix syntax 'editor +N filename', but
         you can configure this by providing your own modified hook if your
         favorite editor supports line-number specifications with a different
         syntax.
 
         -p: this will call the editor with the same data as the previous time
         it was used, regardless of how long ago (in your current session) it
         was.
 
         -r: use 'raw' input.  This option only applies to input taken from the
         user's history.  By default, the 'processed' history is used, so that
         magics are loaded in their transformed version to valid Python.  If
         this option is given, the raw input as typed as the command line is
         used instead.  When you exit the editor, it will be executed by
         IPython's own processor.
 
         -x: do not execute the edited code immediately upon exit. This is
         mainly useful if you are editing programs which need to be called with
         command line arguments, which you can then do using %run.
 
 
         Arguments:
 
         If arguments are given, the following possibilites exist:
 
         - The arguments are numbers or pairs of colon-separated numbers (like
         1 4:8 9). These are interpreted as lines of previous input to be
         loaded into the editor. The syntax is the same of the %macro command.
 
         - If the argument doesn't start with a number, it is evaluated as a
         variable and its contents loaded into the editor. You can thus edit
         any string which contains python code (including the result of
         previous edits).
 
         - If the argument is the name of an object (other than a string),
         IPython will try to locate the file where it was defined and open the
         editor at the point where it is defined. You can use `%edit function`
         to load an editor exactly at the point where 'function' is defined,
         edit it and have the file be executed automatically.
 
         If the object is a macro (see %macro for details), this opens up your
         specified editor with a temporary file containing the macro's data.
         Upon exit, the macro is reloaded with the contents of the file.
 
         Note: opening at an exact line is only supported under Unix, and some
         editors (like kedit and gedit up to Gnome 2.8) do not understand the
         '+NUMBER' parameter necessary for this feature. Good editors like
         (X)Emacs, vi, jed, pico and joe all do.
 
         - If the argument is not found as a variable, IPython will look for a
         file with that name (adding .py if necessary) and load it into the
         editor. It will execute its contents with execfile() when you exit,
         loading any code in the file into your interactive namespace.
 
         After executing your code, %edit will return as output the code you
         typed in the editor (except when it was an existing file). This way
         you can reload the code in further invocations of %edit as a variable,
         via _<NUMBER> or Out[<NUMBER>], where <NUMBER> is the prompt number of
         the output.
 
         Note that %edit is also available through the alias %ed.
 
         This is an example of creating a simple function inside the editor and
         then modifying it. First, start up the editor:
 
         In [1]: ed
         Editing... done. Executing edited code...
         Out[1]: 'def foo():n    print "foo() was defined in an editing session"n'
 
         We can then call the function foo():
 
         In [2]: foo()
         foo() was defined in an editing session
 
         Now we edit foo.  IPython automatically loads the editor with the
         (temporary) file where foo() was previously defined:
 
         In [3]: ed foo
         Editing... done. Executing edited code...
 
         And if we call foo() again we get the modified version:
 
         In [4]: foo()
         foo() has now been changed!
 
         Here is an example of how to edit a code snippet successive
         times. First we call the editor:
 
         In [5]: ed
         Editing... done. Executing edited code...
         hello
         Out[5]: "print 'hello'n"
 
         Now we call it again with the previous output (stored in _):
 
         In [6]: ed _
         Editing... done. Executing edited code...
         hello world
         Out[6]: "print 'hello world'n"
 
         Now we call it with the output #8 (stored in _8, also as Out[8]):
 
         In [7]: ed _8
         Editing... done. Executing edited code...
         hello again
         Out[7]: "print 'hello again'n"
         """
 
         opts,args = self.parse_options(parameter_s,'prn:')
 
         try:
             filename, lineno, _ = CodeMagics._find_edit_target(self.shell, args, opts, last_call)
         except MacroToEdit as e:
             # TODO: Implement macro editing over 2 processes.
             print("Macro editing not yet implemented in 2-process model.")
             return
 
         # Make sure we send to the client an absolute path, in case the working
         # directory of client and kernel don't match
         filename = os.path.abspath(filename)
 
         payload = {
             'source' : 'IPython.kernel.zmq.zmqshell.ZMQInteractiveShell.edit_magic',
             'filename' : filename,
             'line_number' : lineno
         }
         self.shell.payload_manager.write_payload(payload)
 
     # A few magics that are adapted to the specifics of using pexpect and a
     # remote terminal
 
     @line_magic
     def clear(self, arg_s):
         """Clear the terminal."""
         if os.name == 'posix':
             self.shell.system("clear")
         else:
             self.shell.system("cls")
 
     if os.name == 'nt':
         # This is the usual name in windows
         cls = line_magic('cls')(clear)
 
     # Terminal pagers won't work over pexpect, but we do have our own pager
 
     @line_magic
     def less(self, arg_s):
         """Show a file through the pager.
 
         Files ending in .py are syntax-highlighted."""
         if not arg_s:
             raise UsageError('Missing filename.')
 
         cont = open(arg_s).read()
         if arg_s.endswith('.py'):
             cont = self.shell.pycolorize(openpy.read_py_file(arg_s, skip_encoding_cookie=False))
         else:
             cont = open(arg_s).read()
         page.page(cont)
 
     more = line_magic('more')(less)
 
     # Man calls a pager, so we also need to redefine it
     if os.name == 'posix':
         @line_magic
         def man(self, arg_s):
             """Find the man page for the given command and display in pager."""
             page.page(self.shell.getoutput('man %s | col -b' % arg_s,
                                            split=False))
 
     @line_magic
     def connect_info(self, arg_s):
         """Print information for connecting other clients to this kernel
         
         It will print the contents of this session's connection file, as well as
         shortcuts for local clients.
         
         In the simplest case, when called from the most recently launched kernel,
         secondary clients can be connected, simply with:
         
         $> ipython <app> --existing
         
         """
         
         from IPython.core.application import BaseIPythonApplication as BaseIPApp
         
         if BaseIPApp.initialized():
             app = BaseIPApp.instance()
             security_dir = app.profile_dir.security_dir
             profile = app.profile
         else:
             profile = 'default'
             security_dir = ''
         
         try:
             connection_file = get_connection_file()
             info = get_connection_info(unpack=False)
         except Exception as e:
             error("Could not get connection info: %r" % e)
             return
         
         # add profile flag for non-default profile
         profile_flag = "--profile %s" % profile if profile != 'default' else ""
         
         # if it's in the security dir, truncate to basename
         if security_dir == os.path.dirname(connection_file):
             connection_file = os.path.basename(connection_file)
         
         
         print (info + '\n')
         print ("Paste the above JSON into a file, and connect with:\n"
             "    $> ipython <app> --existing <file>\n"
             "or, if you are local, you can connect with just:\n"
             "    $> ipython <app> --existing {0} {1}\n"
             "or even just:\n"
             "    $> ipython <app> --existing {1}\n"
             "if this is the most recent IPython session you have started.".format(
             connection_file, profile_flag
             )
         )
 
     @line_magic
     def qtconsole(self, arg_s):
         """Open a qtconsole connected to this kernel.
         
         Useful for connecting a qtconsole to running notebooks, for better
         debugging.
         """
         
         # %qtconsole should imply bind_kernel for engines:
         try:
             from IPython.parallel import bind_kernel
         except ImportError:
             # technically possible, because parallel has higher pyzmq min-version
             pass
         else:
             bind_kernel()
         
         try:
             p = connect_qtconsole(argv=arg_split(arg_s, os.name=='posix'))
         except Exception as e:
             error("Could not start qtconsole: %r" % e)
             return
     
     @line_magic
     def autosave(self, arg_s):
         """Set the autosave interval in the notebook (in seconds).
         
         The default value is 120, or two minutes.
         ``%autosave 0`` will disable autosave.
         
         This magic only has an effect when called from the notebook interface.
         It has no effect when called in a startup file.
         """
         
         try:
             interval = int(arg_s)
         except ValueError:
             raise UsageError("%%autosave requires an integer, got %r" % arg_s)
         
         # javascript wants milliseconds
         milliseconds = 1000 * interval
         display(Javascript("IPython.notebook.set_autosave_interval(%i)" % milliseconds),
             include=['application/javascript']
         )
         if interval:
             print("Autosaving every %i seconds" % interval)
         else:
             print("Autosave disabled")
 
 
 class ZMQInteractiveShell(InteractiveShell):
     """A subclass of InteractiveShell for ZMQ."""
 
     displayhook_class = Type(ZMQShellDisplayHook)
     display_pub_class = Type(ZMQDisplayPublisher)
     data_pub_class = Type(ZMQDataPublisher)
 
     # Override the traitlet in the parent class, because there's no point using
     # readline for the kernel. Can be removed when the readline code is moved
     # to the terminal frontend.
     colors_force = CBool(True)
     readline_use = CBool(False)
     # autoindent has no meaning in a zmqshell, and attempting to enable it
     # will print a warning in the absence of readline.
     autoindent = CBool(False)
 
     exiter = Instance(ZMQExitAutocall)
     def _exiter_default(self):
         return ZMQExitAutocall(self)
     
     def _exit_now_changed(self, name, old, new):
         """stop eventloop when exit_now fires"""
         if new:
             loop = ioloop.IOLoop.instance()
             loop.add_timeout(time.time()+0.1, loop.stop)
 
     keepkernel_on_exit = None
 
     # Over ZeroMQ, GUI control isn't done with PyOS_InputHook as there is no
     # interactive input being read; we provide event loop support in ipkernel
-    from .eventloops import enable_gui
-    enable_gui = staticmethod(enable_gui)
+    @staticmethod
+    def enable_gui(gui):
+        from .eventloops import enable_gui as real_enable_gui
+        try:
+            real_enable_gui(gui)
+        except ValueError as e:
+            raise UsageError("%s" % e)
 
     def init_environment(self):
         """Configure the user's environment.
 
         """
         env = os.environ
         # These two ensure 'ls' produces nice coloring on BSD-derived systems
         env['TERM'] = 'xterm-color'
         env['CLICOLOR'] = '1'
         # Since normal pagers don't work at all (over pexpect we don't have
         # single-key control of the subprocess), try to disable paging in
         # subprocesses as much as possible.
         env['PAGER'] = 'cat'
         env['GIT_PAGER'] = 'cat'
         
         # And install the payload version of page.
         install_payload_page()
 
     def auto_rewrite_input(self, cmd):
         """Called to show the auto-rewritten input for autocall and friends.
 
         FIXME: this payload is currently not correctly processed by the
         frontend.
         """
         new = self.prompt_manager.render('rewrite') + cmd
         payload = dict(
             source='IPython.kernel.zmq.zmqshell.ZMQInteractiveShell.auto_rewrite_input',
             transformed_input=new,
             )
         self.payload_manager.write_payload(payload)
 
     def ask_exit(self):
         """Engage the exit actions."""
         self.exit_now = True
         payload = dict(
             source='IPython.kernel.zmq.zmqshell.ZMQInteractiveShell.ask_exit',
             exit=True,
             keepkernel=self.keepkernel_on_exit,
             )
         self.payload_manager.write_payload(payload)
 
     def _showtraceback(self, etype, evalue, stb):
 
         exc_content = {
             u'traceback' : stb,
             u'ename' : unicode(etype.__name__),
             u'evalue' : py3compat.safe_unicode(evalue),
         }
 
         dh = self.displayhook
         # Send exception info over pub socket for other clients than the caller
         # to pick up
         topic = None
         if dh.topic:
             topic = dh.topic.replace(b'pyout', b'pyerr')
         
         exc_msg = dh.session.send(dh.pub_socket, u'pyerr', json_clean(exc_content), dh.parent_header, ident=topic)
 
         # FIXME - Hack: store exception info in shell object.  Right now, the
         # caller is reading this info after the fact, we need to fix this logic
         # to remove this hack.  Even uglier, we need to store the error status
         # here, because in the main loop, the logic that sets it is being
         # skipped because runlines swallows the exceptions.
         exc_content[u'status'] = u'error'
         self._reply_content = exc_content
         # /FIXME
 
         return exc_content
 
     def set_next_input(self, text):
         """Send the specified text to the frontend to be presented at the next
         input cell."""
         payload = dict(
             source='IPython.kernel.zmq.zmqshell.ZMQInteractiveShell.set_next_input',
             text=text
         )
         self.payload_manager.write_payload(payload)
     
     #-------------------------------------------------------------------------
     # Things related to magics
     #-------------------------------------------------------------------------
 
     def init_magics(self):
         super(ZMQInteractiveShell, self).init_magics()
         self.register_magics(KernelMagics)
         self.magics_manager.register_alias('ed', 'edit')
 
 
 
 InteractiveShellABC.register(ZMQInteractiveShell)

IPython/terminal/interactiveshell.py

@@ -1,694 +1,697 b''
 # -*- coding: utf-8 -*-
 """Subclass of InteractiveShell for terminal based frontends."""
 
 #-----------------------------------------------------------------------------
 #  Copyright (C) 2001 Janko Hauser <[e-mail]>
 #  Copyright (C) 2001-2007 Fernando Perez. <[e-mail]>
 #  Copyright (C) 2008-2011  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
 #-----------------------------------------------------------------------------
 from __future__ import print_function
 
 import bdb
 import os
 import sys
 
 # We need to use nested to support python 2.6, once we move to >=2.7, we can
 # use the with keyword's new builtin support for nested managers
 try:
     from contextlib import nested
 except:
     from IPython.utils.nested_context import nested
 
 from IPython.core.error import TryNext, UsageError
 from IPython.core.usage import interactive_usage, default_banner
 from IPython.core.inputsplitter import IPythonInputSplitter
 from IPython.core.interactiveshell import InteractiveShell, InteractiveShellABC
 from IPython.core.magic import Magics, magics_class, line_magic
 from IPython.testing.skipdoctest import skip_doctest
 from IPython.utils.encoding import get_stream_enc
 from IPython.utils import py3compat
 from IPython.utils.terminal import toggle_set_term_title, set_term_title
 from IPython.utils.process import abbrev_cwd
 from IPython.utils.warn import warn, error
 from IPython.utils.text import num_ini_spaces, SList, strip_email_quotes
 from IPython.utils.traitlets import Integer, CBool, Unicode
 
 #-----------------------------------------------------------------------------
 # Utilities
 #-----------------------------------------------------------------------------
 
 def get_default_editor():
     try:
         ed = os.environ['EDITOR']
     except KeyError:
         if os.name == 'posix':
             ed = 'vi'  # the only one guaranteed to be there!
         else:
             ed = 'notepad' # same in Windows!
     return ed
 
 
 def get_pasted_lines(sentinel, l_input=py3compat.input):
     """ Yield pasted lines until the user enters the given sentinel value.
     """
     print("Pasting code; enter '%s' alone on the line to stop or use Ctrl-D." \
           % sentinel)
     while True:
         try:
             l = l_input(':')
             if l == sentinel:
                 return
             else:
                 yield l
         except EOFError:
             print('<EOF>')
             return
 
 
 #------------------------------------------------------------------------
 # Terminal-specific magics
 #------------------------------------------------------------------------
 
 @magics_class
 class TerminalMagics(Magics):
     def __init__(self, shell):
         super(TerminalMagics, self).__init__(shell)
         self.input_splitter = IPythonInputSplitter()
         
     def store_or_execute(self, block, name):
         """ Execute a block, or store it in a variable, per the user's request.
         """
         if name:
             # If storing it for further editing
             self.shell.user_ns[name] = SList(block.splitlines())
             print("Block assigned to '%s'" % name)
         else:
             b = self.preclean_input(block)
             self.shell.user_ns['pasted_block'] = b
             self.shell.using_paste_magics = True
             try:
                 self.shell.run_cell(b)
             finally:
                 self.shell.using_paste_magics = False
     
     def preclean_input(self, block):
         lines = block.splitlines()
         while lines and not lines[0].strip():
             lines = lines[1:]
         return strip_email_quotes('\n'.join(lines))
 
     def rerun_pasted(self, name='pasted_block'):
         """ Rerun a previously pasted command.
         """
         b = self.shell.user_ns.get(name)
 
         # Sanity checks
         if b is None:
             raise UsageError('No previous pasted block available')
         if not isinstance(b, basestring):
             raise UsageError(
                 "Variable 'pasted_block' is not a string, can't execute")
 
         print("Re-executing '%s...' (%d chars)"% (b.split('\n',1)[0], len(b)))
         self.shell.run_cell(b)
 
     @line_magic
     def autoindent(self, parameter_s = ''):
         """Toggle autoindent on/off (if available)."""
 
         self.shell.set_autoindent()
         print("Automatic indentation is:",['OFF','ON'][self.shell.autoindent])
 
     @skip_doctest
     @line_magic
     def cpaste(self, parameter_s=''):
         """Paste & execute a pre-formatted code block from clipboard.
 
         You must terminate the block with '--' (two minus-signs) or Ctrl-D
         alone on the line. You can also provide your own sentinel with '%paste
         -s %%' ('%%' is the new sentinel for this operation)
 
         The block is dedented prior to execution to enable execution of method
         definitions. '>' and '+' characters at the beginning of a line are
         ignored, to allow pasting directly from e-mails, diff files and
         doctests (the '...' continuation prompt is also stripped).  The
         executed block is also assigned to variable named 'pasted_block' for
         later editing with '%edit pasted_block'.
 
         You can also pass a variable name as an argument, e.g. '%cpaste foo'.
         This assigns the pasted block to variable 'foo' as string, without
         dedenting or executing it (preceding >>> and + is still stripped)
 
         '%cpaste -r' re-executes the block previously entered by cpaste.
 
         Do not be alarmed by garbled output on Windows (it's a readline bug).
         Just press enter and type -- (and press enter again) and the block
         will be what was just pasted.
 
         IPython statements (magics, shell escapes) are not supported (yet).
 
         See also
         --------
         paste: automatically pull code from clipboard.
 
         Examples
         --------
         ::
 
           In [8]: %cpaste
           Pasting code; enter '--' alone on the line to stop.
           :>>> a = ["world!", "Hello"]
           :>>> print " ".join(sorted(a))
           :--
           Hello world!
         """
         opts, name = self.parse_options(parameter_s, 'rs:', mode='string')
         if 'r' in opts:
             self.rerun_pasted()
             return
 
         sentinel = opts.get('s', '--')
         block = '\n'.join(get_pasted_lines(sentinel))
         self.store_or_execute(block, name)
 
     @line_magic
     def paste(self, parameter_s=''):
         """Paste & execute a pre-formatted code block from clipboard.
 
         The text is pulled directly from the clipboard without user
         intervention and printed back on the screen before execution (unless
         the -q flag is given to force quiet mode).
 
         The block is dedented prior to execution to enable execution of method
         definitions. '>' and '+' characters at the beginning of a line are
         ignored, to allow pasting directly from e-mails, diff files and
         doctests (the '...' continuation prompt is also stripped).  The
         executed block is also assigned to variable named 'pasted_block' for
         later editing with '%edit pasted_block'.
 
         You can also pass a variable name as an argument, e.g. '%paste foo'.
         This assigns the pasted block to variable 'foo' as string, without
         executing it (preceding >>> and + is still stripped).
 
         Options
         -------
 
           -r: re-executes the block previously entered by cpaste.
 
           -q: quiet mode: do not echo the pasted text back to the terminal.
 
         IPython statements (magics, shell escapes) are not supported (yet).
 
         See also
         --------
         cpaste: manually paste code into terminal until you mark its end.
         """
         opts, name = self.parse_options(parameter_s, 'rq', mode='string')
         if 'r' in opts:
             self.rerun_pasted()
             return
         try:
             block = self.shell.hooks.clipboard_get()
         except TryNext as clipboard_exc:
             message = getattr(clipboard_exc, 'args')
             if message:
                 error(message[0])
             else:
                 error('Could not get text from the clipboard.')
             return
 
         # By default, echo back to terminal unless quiet mode is requested
         if 'q' not in opts:
             write = self.shell.write
             write(self.shell.pycolorize(block))
             if not block.endswith('\n'):
                 write('\n')
             write("## -- End pasted text --\n")
 
         self.store_or_execute(block, name)
 
     # Class-level: add a '%cls' magic only on Windows
     if sys.platform == 'win32':
         @line_magic
         def cls(self, s):
             """Clear screen.
             """
             os.system("cls")
 
 #-----------------------------------------------------------------------------
 # Main class
 #-----------------------------------------------------------------------------
 
 class TerminalInteractiveShell(InteractiveShell):
 
     autoedit_syntax = CBool(False, config=True,
         help="auto editing of files with syntax errors.")
     banner = Unicode('')
     banner1 = Unicode(default_banner, config=True,
         help="""The part of the banner to be printed before the profile"""
     )
     banner2 = Unicode('', config=True,
         help="""The part of the banner to be printed after the profile"""
     )
     confirm_exit = CBool(True, config=True,
         help="""
         Set to confirm when you try to exit IPython with an EOF (Control-D
         in Unix, Control-Z/Enter in Windows). By typing 'exit' or 'quit',
         you can force a direct exit without any confirmation.""",
     )
     # This display_banner only controls whether or not self.show_banner()
     # is called when mainloop/interact are called.  The default is False
     # because for the terminal based application, the banner behavior
     # is controlled by Global.display_banner, which IPythonApp looks at
     # to determine if *it* should call show_banner() by hand or not.
     display_banner = CBool(False) # This isn't configurable!
     embedded = CBool(False)
     embedded_active = CBool(False)
     editor = Unicode(get_default_editor(), config=True,
         help="Set the editor used by IPython (default to $EDITOR/vi/notepad)."
     )
     pager = Unicode('less', config=True,
         help="The shell program to be used for paging.")
 
     screen_length = Integer(0, config=True,
         help=
         """Number of lines of your screen, used to control printing of very
         long strings.  Strings longer than this number of lines will be sent
         through a pager instead of directly printed.  The default value for
         this is 0, which means IPython will auto-detect your screen size every
         time it needs to print certain potentially long strings (this doesn't
         change the behavior of the 'print' keyword, it's only triggered
         internally). If for some reason this isn't working well (it needs
         curses support), specify it yourself. Otherwise don't change the
         default.""",
     )
     term_title = CBool(False, config=True,
         help="Enable auto setting the terminal title."
     )
     
     # This `using_paste_magics` is used to detect whether the code is being
     # executed via paste magics functions
     using_paste_magics = CBool(False)
 
     # In the terminal, GUI control is done via PyOS_InputHook
     @staticmethod
     def enable_gui(gui=None, app=None):
         """Switch amongst GUI input hooks by name.
         """
         # Deferred import
         from IPython.lib.inputhook import enable_gui as real_enable_gui
+        try:
         return real_enable_gui(gui, app)
+        except ValueError as e:
+            raise UsageError("%s" % e)
     
     def __init__(self, config=None, ipython_dir=None, profile_dir=None,
                  user_ns=None, user_module=None, custom_exceptions=((),None),
                  usage=None, banner1=None, banner2=None, display_banner=None,
                  **kwargs):
 
         super(TerminalInteractiveShell, self).__init__(
             config=config, ipython_dir=ipython_dir, profile_dir=profile_dir, user_ns=user_ns,
             user_module=user_module, custom_exceptions=custom_exceptions,
             **kwargs
         )
         # use os.system instead of utils.process.system by default,
         # because piped system doesn't make sense in the Terminal:
         self.system = self.system_raw
 
         self.init_term_title()
         self.init_usage(usage)
         self.init_banner(banner1, banner2, display_banner)
 
     #-------------------------------------------------------------------------
     # Overrides of init stages
     #-------------------------------------------------------------------------
 
     def init_display_formatter(self):
         super(TerminalInteractiveShell, self).init_display_formatter()
         # terminal only supports plaintext
         self.display_formatter.active_types = ['text/plain']
 
     #-------------------------------------------------------------------------
     # Things related to the terminal
     #-------------------------------------------------------------------------
 
     @property
     def usable_screen_length(self):
         if self.screen_length == 0:
             return 0
         else:
             num_lines_bot = self.separate_in.count('\n')+1
             return self.screen_length - num_lines_bot
 
     def init_term_title(self):
         # Enable or disable the terminal title.
         if self.term_title:
             toggle_set_term_title(True)
             set_term_title('IPython: ' + abbrev_cwd())
         else:
             toggle_set_term_title(False)
 
     #-------------------------------------------------------------------------
     # Things related to aliases
     #-------------------------------------------------------------------------
 
     def init_alias(self):
         # The parent class defines aliases that can be safely used with any
         # frontend.
         super(TerminalInteractiveShell, self).init_alias()
 
         # Now define aliases that only make sense on the terminal, because they
         # need direct access to the console in a way that we can't emulate in
         # GUI or web frontend
         if os.name == 'posix':
             aliases = [('clear', 'clear'), ('more', 'more'), ('less', 'less'),
                        ('man', 'man')]
         elif os.name == 'nt':
             aliases = [('cls', 'cls')]
 
 
         for name, cmd in aliases:
             self.alias_manager.define_alias(name, cmd)
 
     #-------------------------------------------------------------------------
     # Things related to the banner and usage
     #-------------------------------------------------------------------------
 
     def _banner1_changed(self):
         self.compute_banner()
 
     def _banner2_changed(self):
         self.compute_banner()
 
     def _term_title_changed(self, name, new_value):
         self.init_term_title()
 
     def init_banner(self, banner1, banner2, display_banner):
         if banner1 is not None:
             self.banner1 = banner1
         if banner2 is not None:
             self.banner2 = banner2
         if display_banner is not None:
             self.display_banner = display_banner
         self.compute_banner()
 
     def show_banner(self, banner=None):
         if banner is None:
             banner = self.banner
         self.write(banner)
 
     def compute_banner(self):
         self.banner = self.banner1
         if self.profile and self.profile != 'default':
             self.banner += '\nIPython profile: %s\n' % self.profile
         if self.banner2:
             self.banner += '\n' + self.banner2
 
     def init_usage(self, usage=None):
         if usage is None:
             self.usage = interactive_usage
         else:
             self.usage = usage
 
     #-------------------------------------------------------------------------
     # Mainloop and code execution logic
     #-------------------------------------------------------------------------
 
     def mainloop(self, display_banner=None):
         """Start the mainloop.
 
         If an optional banner argument is given, it will override the
         internally created default banner.
         """
 
         with nested(self.builtin_trap, self.display_trap):
 
             while 1:
                 try:
                     self.interact(display_banner=display_banner)
                     #self.interact_with_readline()
                     # XXX for testing of a readline-decoupled repl loop, call
                     # interact_with_readline above
                     break
                 except KeyboardInterrupt:
                     # this should not be necessary, but KeyboardInterrupt
                     # handling seems rather unpredictable...
                     self.write("\nKeyboardInterrupt in interact()\n")
 
     def _replace_rlhist_multiline(self, source_raw, hlen_before_cell):
         """Store multiple lines as a single entry in history"""
 
         # do nothing without readline or disabled multiline
         if not self.has_readline or not self.multiline_history:
             return hlen_before_cell
 
         # windows rl has no remove_history_item
         if not hasattr(self.readline, "remove_history_item"):
             return hlen_before_cell
 
         # skip empty cells
         if not source_raw.rstrip():
             return hlen_before_cell
 
         # nothing changed do nothing, e.g. when rl removes consecutive dups
         hlen = self.readline.get_current_history_length()
         if hlen == hlen_before_cell:
             return hlen_before_cell
 
         for i in range(hlen - hlen_before_cell):
             self.readline.remove_history_item(hlen - i - 1)
         stdin_encoding = get_stream_enc(sys.stdin, 'utf-8')
         self.readline.add_history(py3compat.unicode_to_str(source_raw.rstrip(),
                                     stdin_encoding))
         return self.readline.get_current_history_length()
 
     def interact(self, display_banner=None):
         """Closely emulate the interactive Python console."""
 
         # batch run -> do not interact
         if self.exit_now:
             return
 
         if display_banner is None:
             display_banner = self.display_banner
 
         if isinstance(display_banner, basestring):
             self.show_banner(display_banner)
         elif display_banner:
             self.show_banner()
 
         more = False
 
         if self.has_readline:
             self.readline_startup_hook(self.pre_readline)
             hlen_b4_cell = self.readline.get_current_history_length()
         else:
             hlen_b4_cell = 0
         # exit_now is set by a call to %Exit or %Quit, through the
         # ask_exit callback.
 
         while not self.exit_now:
             self.hooks.pre_prompt_hook()
             if more:
                 try:
                     prompt = self.prompt_manager.render('in2')
                 except:
                     self.showtraceback()
                 if self.autoindent:
                     self.rl_do_indent = True
 
             else:
                 try:
                     prompt = self.separate_in + self.prompt_manager.render('in')
                 except:
                     self.showtraceback()
             try:
                 line = self.raw_input(prompt)
                 if self.exit_now:
                     # quick exit on sys.std[in|out] close
                     break
                 if self.autoindent:
                     self.rl_do_indent = False
 
             except KeyboardInterrupt:
                 #double-guard against keyboardinterrupts during kbdint handling
                 try:
                     self.write('\nKeyboardInterrupt\n')
                     source_raw = self.input_splitter.source_raw_reset()[1]
                     hlen_b4_cell = \
                         self._replace_rlhist_multiline(source_raw, hlen_b4_cell)
                     more = False
                 except KeyboardInterrupt:
                     pass
             except EOFError:
                 if self.autoindent:
                     self.rl_do_indent = False
                     if self.has_readline:
                         self.readline_startup_hook(None)
                 self.write('\n')
                 self.exit()
             except bdb.BdbQuit:
                 warn('The Python debugger has exited with a BdbQuit exception.\n'
                      'Because of how pdb handles the stack, it is impossible\n'
                      'for IPython to properly format this particular exception.\n'
                      'IPython will resume normal operation.')
             except:
                 # exceptions here are VERY RARE, but they can be triggered
                 # asynchronously by signal handlers, for example.
                 self.showtraceback()
             else:
                 self.input_splitter.push(line)
                 more = self.input_splitter.push_accepts_more()
                 if (self.SyntaxTB.last_syntax_error and
                     self.autoedit_syntax):
                     self.edit_syntax_error()
                 if not more:
                     source_raw = self.input_splitter.source_raw_reset()[1]
                     self.run_cell(source_raw, store_history=True)
                     hlen_b4_cell = \
                         self._replace_rlhist_multiline(source_raw, hlen_b4_cell)
 
         # Turn off the exit flag, so the mainloop can be restarted if desired
         self.exit_now = False
 
     def raw_input(self, prompt=''):
         """Write a prompt and read a line.
 
         The returned line does not include the trailing newline.
         When the user enters the EOF key sequence, EOFError is raised.
 
         Optional inputs:
 
           - prompt(''): a string to be printed to prompt the user.
 
           - continue_prompt(False): whether this line is the first one or a
           continuation in a sequence of inputs.
         """
         # Code run by the user may have modified the readline completer state.
         # We must ensure that our completer is back in place.
 
         if self.has_readline:
             self.set_readline_completer()
         
         # raw_input expects str, but we pass it unicode sometimes
         prompt = py3compat.cast_bytes_py2(prompt)
 
         try:
             line = py3compat.str_to_unicode(self.raw_input_original(prompt))
         except ValueError:
             warn("\n********\nYou or a %run:ed script called sys.stdin.close()"
                  " or sys.stdout.close()!\nExiting IPython!\n")
             self.ask_exit()
             return ""
 
         # Try to be reasonably smart about not re-indenting pasted input more
         # than necessary.  We do this by trimming out the auto-indent initial
         # spaces, if the user's actual input started itself with whitespace.
         if self.autoindent:
             if num_ini_spaces(line) > self.indent_current_nsp:
                 line = line[self.indent_current_nsp:]
                 self.indent_current_nsp = 0
 
         return line
 
     #-------------------------------------------------------------------------
     # Methods to support auto-editing of SyntaxErrors.
     #-------------------------------------------------------------------------
 
     def edit_syntax_error(self):
         """The bottom half of the syntax error handler called in the main loop.
 
         Loop until syntax error is fixed or user cancels.
         """
 
         while self.SyntaxTB.last_syntax_error:
             # copy and clear last_syntax_error
             err = self.SyntaxTB.clear_err_state()
             if not self._should_recompile(err):
                 return
             try:
                 # may set last_syntax_error again if a SyntaxError is raised
                 self.safe_execfile(err.filename,self.user_ns)
             except:
                 self.showtraceback()
             else:
                 try:
                     f = open(err.filename)
                     try:
                         # This should be inside a display_trap block and I
                         # think it is.
                         sys.displayhook(f.read())
                     finally:
                         f.close()
                 except:
                     self.showtraceback()
 
     def _should_recompile(self,e):
         """Utility routine for edit_syntax_error"""
 
         if e.filename in ('<ipython console>','<input>','<string>',
                           '<console>','<BackgroundJob compilation>',
                           None):
 
             return False
         try:
             if (self.autoedit_syntax and
                 not self.ask_yes_no('Return to editor to correct syntax error? '
                               '[Y/n] ','y')):
                 return False
         except EOFError:
             return False
 
         def int0(x):
             try:
                 return int(x)
             except TypeError:
                 return 0
         # always pass integer line and offset values to editor hook
         try:
             self.hooks.fix_error_editor(e.filename,
                 int0(e.lineno),int0(e.offset),e.msg)
         except TryNext:
             warn('Could not open editor')
             return False
         return True
 
     #-------------------------------------------------------------------------
     # Things related to exiting
     #-------------------------------------------------------------------------
 
     def ask_exit(self):
         """ Ask the shell to exit. Can be overiden and used as a callback. """
         self.exit_now = True
 
     def exit(self):
         """Handle interactive exit.
 
         This method calls the ask_exit callback."""
         if self.confirm_exit:
             if self.ask_yes_no('Do you really want to exit ([y]/n)?','y'):
                 self.ask_exit()
         else:
             self.ask_exit()
 
     #-------------------------------------------------------------------------
     # Things related to magics
     #-------------------------------------------------------------------------
 
     def init_magics(self):
         super(TerminalInteractiveShell, self).init_magics()
         self.register_magics(TerminalMagics)
 
     def showindentationerror(self):
         super(TerminalInteractiveShell, self).showindentationerror()
         if not self.using_paste_magics:
             print("If you want to paste code into IPython, try the "
                 "%paste and %cpaste magic functions.")
 
 
 InteractiveShellABC.register(TerminalInteractiveShell)