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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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nbbase.py
179 lines | 5.4 KiB | text/x-python | PythonLexer
"""The basic dict based notebook format.
The Python representation of a notebook is a nested structure of
dictionary subclasses that support attribute access
(IPython.utils.ipstruct.Struct). The functions in this module are merely
helpers to build the structs in the right form.
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
#-----------------------------------------------------------------------------
import pprint
import uuid
from IPython.utils.ipstruct import Struct
#-----------------------------------------------------------------------------
# Code
#-----------------------------------------------------------------------------
class NotebookNode(Struct):
pass
def from_dict(d):
if isinstance(d, dict):
newd = NotebookNode()
for k,v in d.items():
newd[k] = from_dict(v)
return newd
elif isinstance(d, (tuple, list)):
return [from_dict(i) for i in d]
else:
return d
def new_output(output_type=None, output_text=None, output_png=None,
output_html=None, output_svg=None, output_latex=None, output_json=None,
output_javascript=None, output_jpeg=None, prompt_number=None,
etype=None, evalue=None, traceback=None):
"""Create a new code cell with input and output"""
output = NotebookNode()
if output_type is not None:
output.output_type = unicode(output_type)
if output_type != 'pyerr':
if output_text is not None:
output.text = unicode(output_text)
if output_png is not None:
output.png = bytes(output_png)
if output_jpeg is not None:
output.jpeg = bytes(output_jpeg)
if output_html is not None:
output.html = unicode(output_html)
if output_svg is not None:
output.svg = unicode(output_svg)
if output_latex is not None:
output.latex = unicode(output_latex)
if output_json is not None:
output.json = unicode(output_json)
if output_javascript is not None:
output.javascript = unicode(output_javascript)
if output_type == u'pyout':
if prompt_number is not None:
output.prompt_number = int(prompt_number)
if output_type == u'pyerr':
if etype is not None:
output.etype = unicode(etype)
if evalue is not None:
output.evalue = unicode(evalue)
if traceback is not None:
output.traceback = [unicode(frame) for frame in list(traceback)]
return output
def new_code_cell(input=None, prompt_number=None, outputs=None,
language=u'python', collapsed=False):
"""Create a new code cell with input and output"""
cell = NotebookNode()
cell.cell_type = u'code'
if language is not None:
cell.language = unicode(language)
if input is not None:
cell.input = unicode(input)
if prompt_number is not None:
cell.prompt_number = int(prompt_number)
if outputs is None:
cell.outputs = []
else:
cell.outputs = outputs
if collapsed is not None:
cell.collapsed = bool(collapsed)
return cell
def new_text_cell(cell_type, source=None, rendered=None):
"""Create a new text cell."""
cell = NotebookNode()
if source is not None:
cell.source = unicode(source)
if rendered is not None:
cell.rendered = unicode(rendered)
cell.cell_type = cell_type
return cell
def new_worksheet(name=None, cells=None):
"""Create a worksheet by name with with a list of cells."""
ws = NotebookNode()
if name is not None:
ws.name = unicode(name)
if cells is None:
ws.cells = []
else:
ws.cells = list(cells)
return ws
def new_notebook(metadata=None, worksheets=None):
"""Create a notebook by name, id and a list of worksheets."""
nb = NotebookNode()
nb.nbformat = 2
if worksheets is None:
nb.worksheets = []
else:
nb.worksheets = list(worksheets)
if metadata is None:
nb.metadata = new_metadata()
else:
nb.metadata = NotebookNode(metadata)
return nb
def new_metadata(name=None, authors=None, license=None, created=None,
modified=None, gistid=None):
"""Create a new metadata node."""
metadata = NotebookNode()
if name is not None:
metadata.name = unicode(name)
if authors is not None:
metadata.authors = list(authors)
if created is not None:
metadata.created = unicode(created)
if modified is not None:
metadata.modified = unicode(modified)
if license is not None:
metadata.license = unicode(license)
if gistid is not None:
metadata.gistid = unicode(gistid)
return metadata
def new_author(name=None, email=None, affiliation=None, url=None):
"""Create a new author."""
author = NotebookNode()
if name is not None:
author.name = unicode(name)
if email is not None:
author.email = unicode(email)
if affiliation is not None:
author.affiliation = unicode(affiliation)
if url is not None:
author.url = unicode(url)
return author