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Backport PR #4118: ZMQ heartbeat channel: catch EINTR exceptions and continue....
Backport PR #4118: ZMQ heartbeat channel: catch EINTR exceptions and continue. The zmq heartbeat channel exits when it encounters an "Interrupted system call", thereby causing the qtconsole to report that it is not responding, despite the console working perfectly fine. Observed in a large Qt application embedding the ipython qtconsole in KDE desktop. Fixes #2310 Inspired by #501

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frontend_widget.py
784 lines | 32.0 KiB | text/x-python | PythonLexer
from __future__ import print_function
# Standard library imports
from collections import namedtuple
import sys
import uuid
# System library imports
from pygments.lexers import PythonLexer
from IPython.external import qt
from IPython.external.qt import QtCore, QtGui
# Local imports
from IPython.core.inputsplitter import InputSplitter, IPythonInputSplitter
from IPython.core.inputtransformer import classic_prompt
from IPython.core.oinspect import call_tip
from IPython.qt.base_frontend_mixin import BaseFrontendMixin
from IPython.utils.traitlets import Bool, Instance, Unicode
from bracket_matcher import BracketMatcher
from call_tip_widget import CallTipWidget
from completion_lexer import CompletionLexer
from history_console_widget import HistoryConsoleWidget
from pygments_highlighter import PygmentsHighlighter
class FrontendHighlighter(PygmentsHighlighter):
""" A PygmentsHighlighter that understands and ignores prompts.
"""
def __init__(self, frontend):
super(FrontendHighlighter, self).__init__(frontend._control.document())
self._current_offset = 0
self._frontend = frontend
self.highlighting_on = False
def highlightBlock(self, string):
""" Highlight a block of text. Reimplemented to highlight selectively.
"""
if not self.highlighting_on:
return
# The input to this function is a unicode string that may contain
# paragraph break characters, non-breaking spaces, etc. Here we acquire
# the string as plain text so we can compare it.
current_block = self.currentBlock()
string = self._frontend._get_block_plain_text(current_block)
# Decide whether to check for the regular or continuation prompt.
if current_block.contains(self._frontend._prompt_pos):
prompt = self._frontend._prompt
else:
prompt = self._frontend._continuation_prompt
# Only highlight if we can identify a prompt, but make sure not to
# highlight the prompt.
if string.startswith(prompt):
self._current_offset = len(prompt)
string = string[len(prompt):]
super(FrontendHighlighter, self).highlightBlock(string)
def rehighlightBlock(self, block):
""" Reimplemented to temporarily enable highlighting if disabled.
"""
old = self.highlighting_on
self.highlighting_on = True
super(FrontendHighlighter, self).rehighlightBlock(block)
self.highlighting_on = old
def setFormat(self, start, count, format):
""" Reimplemented to highlight selectively.
"""
start += self._current_offset
super(FrontendHighlighter, self).setFormat(start, count, format)
class FrontendWidget(HistoryConsoleWidget, BaseFrontendMixin):
""" A Qt frontend for a generic Python kernel.
"""
# The text to show when the kernel is (re)started.
banner = Unicode(config=True)
# An option and corresponding signal for overriding the default kernel
# interrupt behavior.
custom_interrupt = Bool(False)
custom_interrupt_requested = QtCore.Signal()
# An option and corresponding signals for overriding the default kernel
# restart behavior.
custom_restart = Bool(False)
custom_restart_kernel_died = QtCore.Signal(float)
custom_restart_requested = QtCore.Signal()
# Whether to automatically show calltips on open-parentheses.
enable_calltips = Bool(True, config=True,
help="Whether to draw information calltips on open-parentheses.")
clear_on_kernel_restart = Bool(True, config=True,
help="Whether to clear the console when the kernel is restarted")
confirm_restart = Bool(True, config=True,
help="Whether to ask for user confirmation when restarting kernel")
# Emitted when a user visible 'execute_request' has been submitted to the
# kernel from the FrontendWidget. Contains the code to be executed.
executing = QtCore.Signal(object)
# Emitted when a user-visible 'execute_reply' has been received from the
# kernel and processed by the FrontendWidget. Contains the response message.
executed = QtCore.Signal(object)
# Emitted when an exit request has been received from the kernel.
exit_requested = QtCore.Signal(object)
# Protected class variables.
_prompt_transformer = IPythonInputSplitter(physical_line_transforms=[classic_prompt()],
logical_line_transforms=[],
python_line_transforms=[],
)
_CallTipRequest = namedtuple('_CallTipRequest', ['id', 'pos'])
_CompletionRequest = namedtuple('_CompletionRequest', ['id', 'pos'])
_ExecutionRequest = namedtuple('_ExecutionRequest', ['id', 'kind'])
_input_splitter_class = InputSplitter
_local_kernel = False
_highlighter = Instance(FrontendHighlighter)
#---------------------------------------------------------------------------
# 'object' interface
#---------------------------------------------------------------------------
def __init__(self, *args, **kw):
super(FrontendWidget, self).__init__(*args, **kw)
# FIXME: remove this when PySide min version is updated past 1.0.7
# forcefully disable calltips if PySide is < 1.0.7, because they crash
if qt.QT_API == qt.QT_API_PYSIDE:
import PySide
if PySide.__version_info__ < (1,0,7):
self.log.warn("PySide %s < 1.0.7 detected, disabling calltips" % PySide.__version__)
self.enable_calltips = False
# FrontendWidget protected variables.
self._bracket_matcher = BracketMatcher(self._control)
self._call_tip_widget = CallTipWidget(self._control)
self._completion_lexer = CompletionLexer(PythonLexer())
self._copy_raw_action = QtGui.QAction('Copy (Raw Text)', None)
self._hidden = False
self._highlighter = FrontendHighlighter(self)
self._input_splitter = self._input_splitter_class()
self._kernel_manager = None
self._kernel_client = None
self._request_info = {}
self._request_info['execute'] = {};
self._callback_dict = {}
# Configure the ConsoleWidget.
self.tab_width = 4
self._set_continuation_prompt('... ')
# Configure the CallTipWidget.
self._call_tip_widget.setFont(self.font)
self.font_changed.connect(self._call_tip_widget.setFont)
# Configure actions.
action = self._copy_raw_action
key = QtCore.Qt.CTRL | QtCore.Qt.SHIFT | QtCore.Qt.Key_C
action.setEnabled(False)
action.setShortcut(QtGui.QKeySequence(key))
action.setShortcutContext(QtCore.Qt.WidgetWithChildrenShortcut)
action.triggered.connect(self.copy_raw)
self.copy_available.connect(action.setEnabled)
self.addAction(action)
# Connect signal handlers.
document = self._control.document()
document.contentsChange.connect(self._document_contents_change)
# Set flag for whether we are connected via localhost.
self._local_kernel = kw.get('local_kernel',
FrontendWidget._local_kernel)
#---------------------------------------------------------------------------
# 'ConsoleWidget' public interface
#---------------------------------------------------------------------------
def copy(self):
""" Copy the currently selected text to the clipboard, removing prompts.
"""
if self._page_control is not None and self._page_control.hasFocus():
self._page_control.copy()
elif self._control.hasFocus():
text = self._control.textCursor().selection().toPlainText()
if text:
text = self._prompt_transformer.transform_cell(text)
QtGui.QApplication.clipboard().setText(text)
else:
self.log.debug("frontend widget : unknown copy target")
#---------------------------------------------------------------------------
# 'ConsoleWidget' abstract interface
#---------------------------------------------------------------------------
def _is_complete(self, source, interactive):
""" Returns whether 'source' can be completely processed and a new
prompt created. When triggered by an Enter/Return key press,
'interactive' is True; otherwise, it is False.
"""
self._input_splitter.reset()
complete = self._input_splitter.push(source)
if interactive:
complete = not self._input_splitter.push_accepts_more()
return complete
def _execute(self, source, hidden):
""" Execute 'source'. If 'hidden', do not show any output.
See parent class :meth:`execute` docstring for full details.
"""
msg_id = self.kernel_client.execute(source, hidden)
self._request_info['execute'][msg_id] = self._ExecutionRequest(msg_id, 'user')
self._hidden = hidden
if not hidden:
self.executing.emit(source)
def _prompt_started_hook(self):
""" Called immediately after a new prompt is displayed.
"""
if not self._reading:
self._highlighter.highlighting_on = True
def _prompt_finished_hook(self):
""" Called immediately after a prompt is finished, i.e. when some input
will be processed and a new prompt displayed.
"""
# Flush all state from the input splitter so the next round of
# reading input starts with a clean buffer.
self._input_splitter.reset()
if not self._reading:
self._highlighter.highlighting_on = False
def _tab_pressed(self):
""" Called when the tab key is pressed. Returns whether to continue
processing the event.
"""
# Perform tab completion if:
# 1) The cursor is in the input buffer.
# 2) There is a non-whitespace character before the cursor.
text = self._get_input_buffer_cursor_line()
if text is None:
return False
complete = bool(text[:self._get_input_buffer_cursor_column()].strip())
if complete:
self._complete()
return not complete
#---------------------------------------------------------------------------
# 'ConsoleWidget' protected interface
#---------------------------------------------------------------------------
def _context_menu_make(self, pos):
""" Reimplemented to add an action for raw copy.
"""
menu = super(FrontendWidget, self)._context_menu_make(pos)
for before_action in menu.actions():
if before_action.shortcut().matches(QtGui.QKeySequence.Paste) == \
QtGui.QKeySequence.ExactMatch:
menu.insertAction(before_action, self._copy_raw_action)
break
return menu
def request_interrupt_kernel(self):
if self._executing:
self.interrupt_kernel()
def request_restart_kernel(self):
message = 'Are you sure you want to restart the kernel?'
self.restart_kernel(message, now=False)
def _event_filter_console_keypress(self, event):
""" Reimplemented for execution interruption and smart backspace.
"""
key = event.key()
if self._control_key_down(event.modifiers(), include_command=False):
if key == QtCore.Qt.Key_C and self._executing:
self.request_interrupt_kernel()
return True
elif key == QtCore.Qt.Key_Period:
self.request_restart_kernel()
return True
elif not event.modifiers() & QtCore.Qt.AltModifier:
# Smart backspace: remove four characters in one backspace if:
# 1) everything left of the cursor is whitespace
# 2) the four characters immediately left of the cursor are spaces
if key == QtCore.Qt.Key_Backspace:
col = self._get_input_buffer_cursor_column()
cursor = self._control.textCursor()
if col > 3 and not cursor.hasSelection():
text = self._get_input_buffer_cursor_line()[:col]
if text.endswith(' ') and not text.strip():
cursor.movePosition(QtGui.QTextCursor.Left,
QtGui.QTextCursor.KeepAnchor, 4)
cursor.removeSelectedText()
return True
return super(FrontendWidget, self)._event_filter_console_keypress(event)
def _insert_continuation_prompt(self, cursor):
""" Reimplemented for auto-indentation.
"""
super(FrontendWidget, self)._insert_continuation_prompt(cursor)
cursor.insertText(' ' * self._input_splitter.indent_spaces)
#---------------------------------------------------------------------------
# 'BaseFrontendMixin' abstract interface
#---------------------------------------------------------------------------
def _handle_complete_reply(self, rep):
""" Handle replies for tab completion.
"""
self.log.debug("complete: %s", rep.get('content', ''))
cursor = self._get_cursor()
info = self._request_info.get('complete')
if info and info.id == rep['parent_header']['msg_id'] and \
info.pos == cursor.position():
text = '.'.join(self._get_context())
cursor.movePosition(QtGui.QTextCursor.Left, n=len(text))
self._complete_with_items(cursor, rep['content']['matches'])
def _silent_exec_callback(self, expr, callback):
"""Silently execute `expr` in the kernel and call `callback` with reply
the `expr` is evaluated silently in the kernel (without) output in
the frontend. Call `callback` with the
`repr <http://docs.python.org/library/functions.html#repr> `_ as first argument
Parameters
----------
expr : string
valid string to be executed by the kernel.
callback : function
function accepting one argument, as a string. The string will be
the `repr` of the result of evaluating `expr`
The `callback` is called with the `repr()` of the result of `expr` as
first argument. To get the object, do `eval()` on the passed value.
See Also
--------
_handle_exec_callback : private method, deal with calling callback with reply
"""
# generate uuid, which would be used as an indication of whether or
# not the unique request originated from here (can use msg id ?)
local_uuid = str(uuid.uuid1())
msg_id = self.kernel_client.execute('',
silent=True, user_expressions={ local_uuid:expr })
self._callback_dict[local_uuid] = callback
self._request_info['execute'][msg_id] = self._ExecutionRequest(msg_id, 'silent_exec_callback')
def _handle_exec_callback(self, msg):
"""Execute `callback` corresponding to `msg` reply, after ``_silent_exec_callback``
Parameters
----------
msg : raw message send by the kernel containing an `user_expressions`
and having a 'silent_exec_callback' kind.
Notes
-----
This function will look for a `callback` associated with the
corresponding message id. Association has been made by
`_silent_exec_callback`. `callback` is then called with the `repr()`
of the value of corresponding `user_expressions` as argument.
`callback` is then removed from the known list so that any message
coming again with the same id won't trigger it.
"""
user_exp = msg['content'].get('user_expressions')
if not user_exp:
return
for expression in user_exp:
if expression in self._callback_dict:
self._callback_dict.pop(expression)(user_exp[expression])
def _handle_execute_reply(self, msg):
""" Handles replies for code execution.
"""
self.log.debug("execute: %s", msg.get('content', ''))
msg_id = msg['parent_header']['msg_id']
info = self._request_info['execute'].get(msg_id)
# unset reading flag, because if execute finished, raw_input can't
# still be pending.
self._reading = False
if info and info.kind == 'user' and not self._hidden:
# Make sure that all output from the SUB channel has been processed
# before writing a new prompt.
self.kernel_client.iopub_channel.flush()
# Reset the ANSI style information to prevent bad text in stdout
# from messing up our colors. We're not a true terminal so we're
# allowed to do this.
if self.ansi_codes:
self._ansi_processor.reset_sgr()
content = msg['content']
status = content['status']
if status == 'ok':
self._process_execute_ok(msg)
elif status == 'error':
self._process_execute_error(msg)
elif status == 'aborted':
self._process_execute_abort(msg)
self._show_interpreter_prompt_for_reply(msg)
self.executed.emit(msg)
self._request_info['execute'].pop(msg_id)
elif info and info.kind == 'silent_exec_callback' and not self._hidden:
self._handle_exec_callback(msg)
self._request_info['execute'].pop(msg_id)
else:
super(FrontendWidget, self)._handle_execute_reply(msg)
def _handle_input_request(self, msg):
""" Handle requests for raw_input.
"""
self.log.debug("input: %s", msg.get('content', ''))
if self._hidden:
raise RuntimeError('Request for raw input during hidden execution.')
# Make sure that all output from the SUB channel has been processed
# before entering readline mode.
self.kernel_client.iopub_channel.flush()
def callback(line):
self.kernel_client.stdin_channel.input(line)
if self._reading:
self.log.debug("Got second input request, assuming first was interrupted.")
self._reading = False
self._readline(msg['content']['prompt'], callback=callback)
def _kernel_restarted_message(self, died=True):
msg = "Kernel died, restarting" if died else "Kernel restarting"
self._append_html("<br>%s<hr><br>" % msg,
before_prompt=False
)
def _handle_kernel_died(self, since_last_heartbeat):
"""Handle the kernel's death (if we do not own the kernel).
"""
self.log.warn("kernel died: %s", since_last_heartbeat)
if self.custom_restart:
self.custom_restart_kernel_died.emit(since_last_heartbeat)
else:
self._kernel_restarted_message(died=True)
self.reset()
def _handle_kernel_restarted(self, died=True):
"""Notice that the autorestarter restarted the kernel.
There's nothing to do but show a message.
"""
self.log.warn("kernel restarted")
self._kernel_restarted_message(died=died)
self.reset()
def _handle_object_info_reply(self, rep):
""" Handle replies for call tips.
"""
self.log.debug("oinfo: %s", rep.get('content', ''))
cursor = self._get_cursor()
info = self._request_info.get('call_tip')
if info and info.id == rep['parent_header']['msg_id'] and \
info.pos == cursor.position():
# Get the information for a call tip. For now we format the call
# line as string, later we can pass False to format_call and
# syntax-highlight it ourselves for nicer formatting in the
# calltip.
content = rep['content']
# if this is from pykernel, 'docstring' will be the only key
if content.get('ismagic', False):
# Don't generate a call-tip for magics. Ideally, we should
# generate a tooltip, but not on ( like we do for actual
# callables.
call_info, doc = None, None
else:
call_info, doc = call_tip(content, format_call=True)
if call_info or doc:
self._call_tip_widget.show_call_info(call_info, doc)
def _handle_pyout(self, msg):
""" Handle display hook output.
"""
self.log.debug("pyout: %s", msg.get('content', ''))
if not self._hidden and self._is_from_this_session(msg):
text = msg['content']['data']
self._append_plain_text(text + '\n', before_prompt=True)
def _handle_stream(self, msg):
""" Handle stdout, stderr, and stdin.
"""
self.log.debug("stream: %s", msg.get('content', ''))
if not self._hidden and self._is_from_this_session(msg):
# Most consoles treat tabs as being 8 space characters. Convert tabs
# to spaces so that output looks as expected regardless of this
# widget's tab width.
text = msg['content']['data'].expandtabs(8)
self._append_plain_text(text, before_prompt=True)
self._control.moveCursor(QtGui.QTextCursor.End)
def _handle_shutdown_reply(self, msg):
""" Handle shutdown signal, only if from other console.
"""
self.log.warn("shutdown: %s", msg.get('content', ''))
restart = msg.get('content', {}).get('restart', False)
if not self._hidden and not self._is_from_this_session(msg):
# got shutdown reply, request came from session other than ours
if restart:
# someone restarted the kernel, handle it
self._handle_kernel_restarted(died=False)
else:
# kernel was shutdown permanently
# this triggers exit_requested if the kernel was local,
# and a dialog if the kernel was remote,
# so we don't suddenly clear the qtconsole without asking.
if self._local_kernel:
self.exit_requested.emit(self)
else:
title = self.window().windowTitle()
reply = QtGui.QMessageBox.question(self, title,
"Kernel has been shutdown permanently. "
"Close the Console?",
QtGui.QMessageBox.Yes,QtGui.QMessageBox.No)
if reply == QtGui.QMessageBox.Yes:
self.exit_requested.emit(self)
def _handle_status(self, msg):
"""Handle status message"""
# This is where a busy/idle indicator would be triggered,
# when we make one.
state = msg['content'].get('execution_state', '')
if state == 'starting':
# kernel started while we were running
if self._executing:
self._handle_kernel_restarted(died=True)
elif state == 'idle':
pass
elif state == 'busy':
pass
def _started_channels(self):
""" Called when the KernelManager channels have started listening or
when the frontend is assigned an already listening KernelManager.
"""
self.reset(clear=True)
#---------------------------------------------------------------------------
# 'FrontendWidget' public interface
#---------------------------------------------------------------------------
def copy_raw(self):
""" Copy the currently selected text to the clipboard without attempting
to remove prompts or otherwise alter the text.
"""
self._control.copy()
def execute_file(self, path, hidden=False):
""" Attempts to execute file with 'path'. If 'hidden', no output is
shown.
"""
self.execute('execfile(%r)' % path, hidden=hidden)
def interrupt_kernel(self):
""" Attempts to interrupt the running kernel.
Also unsets _reading flag, to avoid runtime errors
if raw_input is called again.
"""
if self.custom_interrupt:
self._reading = False
self.custom_interrupt_requested.emit()
elif self.kernel_manager:
self._reading = False
self.kernel_manager.interrupt_kernel()
else:
self._append_plain_text('Cannot interrupt a kernel I did not start.\n')
def reset(self, clear=False):
""" Resets the widget to its initial state if ``clear`` parameter
is True, otherwise
prints a visual indication of the fact that the kernel restarted, but
does not clear the traces from previous usage of the kernel before it
was restarted. With ``clear=True``, it is similar to ``%clear``, but
also re-writes the banner and aborts execution if necessary.
"""
if self._executing:
self._executing = False
self._request_info['execute'] = {}
self._reading = False
self._highlighter.highlighting_on = False
if clear:
self._control.clear()
self._append_plain_text(self.banner)
# update output marker for stdout/stderr, so that startup
# messages appear after banner:
self._append_before_prompt_pos = self._get_cursor().position()
self._show_interpreter_prompt()
def restart_kernel(self, message, now=False):
""" Attempts to restart the running kernel.
"""
# FIXME: now should be configurable via a checkbox in the dialog. Right
# now at least the heartbeat path sets it to True and the manual restart
# to False. But those should just be the pre-selected states of a
# checkbox that the user could override if so desired. But I don't know
# enough Qt to go implementing the checkbox now.
if self.custom_restart:
self.custom_restart_requested.emit()
return
if self.kernel_manager:
# Pause the heart beat channel to prevent further warnings.
self.kernel_client.hb_channel.pause()
# Prompt the user to restart the kernel. Un-pause the heartbeat if
# they decline. (If they accept, the heartbeat will be un-paused
# automatically when the kernel is restarted.)
if self.confirm_restart:
buttons = QtGui.QMessageBox.Yes | QtGui.QMessageBox.No
result = QtGui.QMessageBox.question(self, 'Restart kernel?',
message, buttons)
do_restart = result == QtGui.QMessageBox.Yes
else:
# confirm_restart is False, so we don't need to ask user
# anything, just do the restart
do_restart = True
if do_restart:
try:
self.kernel_manager.restart_kernel(now=now)
except RuntimeError as e:
self._append_plain_text(
'Error restarting kernel: %s\n' % e,
before_prompt=True
)
else:
self._append_html("<br>Restarting kernel...\n<hr><br>",
before_prompt=True,
)
else:
self.kernel_client.hb_channel.unpause()
else:
self._append_plain_text(
'Cannot restart a Kernel I did not start\n',
before_prompt=True
)
#---------------------------------------------------------------------------
# 'FrontendWidget' protected interface
#---------------------------------------------------------------------------
def _call_tip(self):
""" Shows a call tip, if appropriate, at the current cursor location.
"""
# Decide if it makes sense to show a call tip
if not self.enable_calltips:
return False
cursor = self._get_cursor()
cursor.movePosition(QtGui.QTextCursor.Left)
if cursor.document().characterAt(cursor.position()) != '(':
return False
context = self._get_context(cursor)
if not context:
return False
# Send the metadata request to the kernel
name = '.'.join(context)
msg_id = self.kernel_client.object_info(name)
pos = self._get_cursor().position()
self._request_info['call_tip'] = self._CallTipRequest(msg_id, pos)
return True
def _complete(self):
""" Performs completion at the current cursor location.
"""
context = self._get_context()
if context:
# Send the completion request to the kernel
msg_id = self.kernel_client.complete(
'.'.join(context), # text
self._get_input_buffer_cursor_line(), # line
self._get_input_buffer_cursor_column(), # cursor_pos
self.input_buffer) # block
pos = self._get_cursor().position()
info = self._CompletionRequest(msg_id, pos)
self._request_info['complete'] = info
def _get_context(self, cursor=None):
""" Gets the context for the specified cursor (or the current cursor
if none is specified).
"""
if cursor is None:
cursor = self._get_cursor()
cursor.movePosition(QtGui.QTextCursor.StartOfBlock,
QtGui.QTextCursor.KeepAnchor)
text = cursor.selection().toPlainText()
return self._completion_lexer.get_context(text)
def _process_execute_abort(self, msg):
""" Process a reply for an aborted execution request.
"""
self._append_plain_text("ERROR: execution aborted\n")
def _process_execute_error(self, msg):
""" Process a reply for an execution request that resulted in an error.
"""
content = msg['content']
# If a SystemExit is passed along, this means exit() was called - also
# all the ipython %exit magic syntax of '-k' to be used to keep
# the kernel running
if content['ename']=='SystemExit':
keepkernel = content['evalue']=='-k' or content['evalue']=='True'
self._keep_kernel_on_exit = keepkernel
self.exit_requested.emit(self)
else:
traceback = ''.join(content['traceback'])
self._append_plain_text(traceback)
def _process_execute_ok(self, msg):
""" Process a reply for a successful execution request.
"""
payload = msg['content']['payload']
for item in payload:
if not self._process_execute_payload(item):
warning = 'Warning: received unknown payload of type %s'
print(warning % repr(item['source']))
def _process_execute_payload(self, item):
""" Process a single payload item from the list of payload items in an
execution reply. Returns whether the payload was handled.
"""
# The basic FrontendWidget doesn't handle payloads, as they are a
# mechanism for going beyond the standard Python interpreter model.
return False
def _show_interpreter_prompt(self):
""" Shows a prompt for the interpreter.
"""
self._show_prompt('>>> ')
def _show_interpreter_prompt_for_reply(self, msg):
""" Shows a prompt for the interpreter given an 'execute_reply' message.
"""
self._show_interpreter_prompt()
#------ Signal handlers ----------------------------------------------------
def _document_contents_change(self, position, removed, added):
""" Called whenever the document's content changes. Display a call tip
if appropriate.
"""
# Calculate where the cursor should be *after* the change:
position += added
document = self._control.document()
if position == self._get_cursor().position():
self._call_tip()
#------ Trait default initializers -----------------------------------------
def _banner_default(self):
""" Returns the standard Python banner.
"""
banner = 'Python %s on %s\nType "help", "copyright", "credits" or ' \
'"license" for more information.'
return banner % (sys.version, sys.platform)