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Backport PR #2294: inputhook_qt4: Use QEventLoop instead of starting up the QCoreApplication...
Backport PR #2294: inputhook_qt4: Use QEventLoop instead of starting up the QCoreApplication I referenced this branch in #2080 and was letting it sit for a little while, but I have decided to make it a full pull request to get some additional visibility. Essentially our Qt event loop mechanism repeatedly starts and quits a `QCoreApplication` object. Unfortunately the `QCoreApplication::quit` slot has a lot of unintended side effects (like emitting an `aboutToQuit` signal which closes all open file dialogs). For our input hook, we _might_ be able to get by with just using a `QEventLoop` whose quit slot is much simpler and less destructive. For a little bit of background on why one might want to just use `QEventLoop::exec`, let's examine what `QCoreApplication::exec` does: ```c++ int QCoreApplication::exec() { if (!QCoreApplicationPrivate::checkInstance("exec")) return -1; // ... [some assertions] threadData->quitNow = false; QEventLoop eventLoop; self->d_func()->in_exec = true; self->d_func()->aboutToQuitEmitted = false; int returnCode = eventLoop.exec(); threadData->quitNow = false; if (self) { self->d_func()->in_exec = false; if (!self->d_func()->aboutToQuitEmitted) emit self->aboutToQuit(); self->d_func()->aboutToQuitEmitted = true; sendPostedEvents(0, QEvent::DeferredDelete); } return returnCode; } ``` As far as I can tell, it's a small wrapper around `QEventLoop::exec` which also: * Sets some variables regarding the current status * Emits an `aboutToQuit` signal right before the function returns (which is the root cause of @denisri's problem in #2080). Historically, our Qt event loop is a python implementation of the (win 32) input hook supplied with the PyQt4 source (see qtcore_input_hook` in `python-qt4/sip/QtCore/qcoreapplication.sip`), which more or less dates to a [mailing list post](http://www.riverbankcomputing.com/pipermail/pyqt/2007-July/016512.html) from July 2007.
Matthias BUSSONNIER - - Load All Authors

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r5390:c82649ea
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test_linefrontend.py
37 lines | 1.1 KiB | text/x-python | PythonLexer
/ IPython / deathrow / oldfrontend / tests / test_linefrontend.py
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Gael Varoquaux
BUG: Integrate bug fixes from Enthought
 r1887 # encoding: utf-8
"""
Bernardo B. Marques
remove all trailling spaces
 r4872 Test the LineFrontEnd
Gael Varoquaux
BUG: Integrate bug fixes from Enthought
 r1887 """
__docformat__ = "restructuredtext en"
#-------------------------------------------------------------------------------
Matthias BUSSONNIER
update copyright to 2011/20xx-2011...
 r5390 # Copyright (C) 2008-2011 The IPython Development Team
Gael Varoquaux
BUG: Integrate bug fixes from Enthought
 r1887 #
# Distributed under the terms of the BSD License. The full license is
# in the file COPYING, distributed as part of this software.
#-------------------------------------------------------------------------------
from IPython.frontend.linefrontendbase import LineFrontEndBase
from copy import deepcopy
Gael Varoquaux
Take in account remarks by Fernando on code review
 r1947 import nose.tools as nt
Gael Varoquaux
BUG: Integrate bug fixes from Enthought
 r1887
class ConcreteLineFrontEnd(LineFrontEndBase):
""" A concrete class to test the LineFrontEndBase.
"""
def capture_output(self):
pass
def release_output(self):
pass
def test_is_complete():
""" Tests line completion heuristic.
"""
frontend = ConcreteLineFrontEnd()
Gael Varoquaux
Take in account remarks by Fernando on code review
 r1947 yield nt.assert_true, not frontend.is_complete('for x in \\')
yield nt.assert_true, not frontend.is_complete('for x in (1, ):')
yield nt.assert_true, frontend.is_complete('for x in (1, ):\n pass')
Gael Varoquaux
BUG: Integrate bug fixes from Enthought
 r1887