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Python Qtconsole: QApp = QCoreApplication.instance() returns None on Linux and a valid QApplication on Windows

I have software which has a GUI interface and a command line interface. What it should do is detect if it is being run in a qtconsole. If it is, it will not create a new QApplication and show the GUI in a non-blocking manner. After the script exists, there will be a cmd object where the user can interact with things on a lower level. 

from PyQt4.QtCore import QCoreApplication
from PyQt4.Qt import QApplication
import sys

QApp = QCoreApplication.instance() 
new_qapp_bit = False
if QApp == None:
    print 'running without the qt console'
    new_qapp_bit = True
    QApp = QApplication(sys.argv)
else:
    print 'found the qt console'

cmd = MyCMDInterface(use_gui=True)

if new_qapp_bit
    sys.exit(QApp.exec_())

On windows this works perfectly, QCoreApplication.instance() returns a valid QApplication and everything goes according to plan, but on Linux and Mac it returns None. I've been hacking at this awhile, and I'm not seeing any answers.

Solution

  • The problem was I forgot the '--pylab=qt ' argument when I ran 

    ipython qtconsole --pylab=qt --color=Linux -c "%run main.py"