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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.

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__init__.py
78 lines | 2.5 KiB | text/x-python | PythonLexer
"""The main API for the v2 notebook format.
Authors:
* Brian Granger
"""
#-----------------------------------------------------------------------------
# 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 .nbbase import (
NotebookNode,
new_code_cell, new_text_cell, new_notebook, new_output, new_worksheet,
new_metadata, new_author
)
from .nbjson import reads as reads_json, writes as writes_json
from .nbjson import reads as read_json, writes as write_json
from .nbjson import to_notebook as to_notebook_json
from .nbxml import reads as reads_xml
from .nbxml import reads as read_xml
from .nbxml import to_notebook as to_notebook_xml
from .nbpy import reads as reads_py, writes as writes_py
from .nbpy import reads as read_py, writes as write_py
from .nbpy import to_notebook as to_notebook_py
from .convert import convert_to_this_nbformat
#-----------------------------------------------------------------------------
# Code
#-----------------------------------------------------------------------------
def parse_filename(fname):
"""Parse a notebook filename.
This function takes a notebook filename and returns the notebook
format (json/py) and the notebook name. This logic can be
summarized as follows:
* notebook.ipynb -> (notebook.ipynb, notebook, json)
* notebook.json -> (notebook.json, notebook, json)
* notebook.py -> (notebook.py, notebook, py)
* notebook -> (notebook.ipynb, notebook, json)
Parameters
----------
fname : unicode
The notebook filename. The filename can use a specific filename
extention (.ipynb, .json, .py) or none, in which case .ipynb will
be assumed.
Returns
-------
(fname, name, format) : (unicode, unicode, unicode)
The filename, notebook name and format.
"""
if fname.endswith(u'.ipynb'):
format = u'json'
elif fname.endswith(u'.json'):
format = u'json'
elif fname.endswith(u'.py'):
format = u'py'
else:
fname = fname + u'.ipynb'
format = u'json'
name = fname.split('.')[0]
return fname, name, format