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Example of adding input transformers....
Example of adding input transformers. Closes gh-4709

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eventloops.py
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# 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 _on_os_x_10_9():
import platform
from distutils.version import LooseVersion as V
return sys.platform == 'darwin' and V(platform.mac_ver()[0]) >= V('10.9')
def _notify_stream_qt(kernel, stream):
from IPython.external.qt_for_kernel import QtCore
if _on_os_x_10_9() and kernel._darwin_app_nap:
from IPython.external.appnope import nope_scope as context
else:
from IPython.core.interactiveshell import NoOpContext as context
def process_stream_events():
while stream.getsockopt(zmq.EVENTS) & zmq.POLLIN:
with context():
kernel.do_one_iteration()
fd = stream.getsockopt(zmq.FD)
notifier = QtCore.QSocketNotifier(fd, QtCore.QSocketNotifier.Read, kernel.app)
notifier.activated.connect(process_stream_events)
def loop_qt4(kernel):
"""Start a kernel with PyQt4 event loop integration."""
from IPython.lib.guisupport import get_app_qt4, start_event_loop_qt4
kernel.app = get_app_qt4([" "])
kernel.app.setQuitOnLastWindowClosed(False)
for s in kernel.shell_streams:
_notify_stream_qt(kernel, s)
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
if _on_os_x_10_9() and kernel._darwin_app_nap:
# we don't hook up App Nap contexts for Wx,
# just disable it outright.
from IPython.external.appnope import nope
nope()
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."""
try:
from tkinter import Tk # Py 3
except ImportError:
from Tkinter import Tk # Py 2
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 = 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:
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