[IPython-dev] GUI support: conflicts between IPython 0.11 and Matplotlib/ETS

Hans Meine hans_meine@gmx....
Fri Feb 12 05:25:04 CST 2010

On Friday 12 February 2010 12:11:04 Gael Varoquaux wrote:
> On Fri, Feb 12, 2010 at 12:06:50PM +0100, Hans Meine wrote:
> > Do I?  I see it more like a minimal setup function for opening the main
> > window, which is all I care about.  The QApplication line is only there
> > to make the stuff below work (with Qt, as with most toolkits AFAIK, I
> > would otherwise get an error because the widgets will rely on global
> > state being initialized by the application constructor).
> Use:
>     app = QtGui.QApplication.instance()
> That should suit your needs and avoid creating an QApplication if it
> already exists.

Thanks for the hint, but the docs say:
  "If no instance has been allocated, null is returned."

Furthermore, what about app.exec_?  I thought I needed sth. like:

if __name__ == "__main__":
	hasApp = QtGui.QApplication.instance()
	if not hasApp:
		import sys
		app = QtGui.QApplication(sys.argv)

	mw = BeverageMainWindow()
	mw.resize(800, 600)

	if not hasApp:

That's OK, I can do that, but I would still prefer not to have to change every 
application just for the occasional debugging session in ipython.

And how do you want to communicate this to all ipython users?  I mean - there 
needs to be some documentation about this boilerplate code for every toolkit, 
and every user needs to be aware of this and get it right.

I fully agree that the above code has a much better design, is more well-
behaved, but you know very well that most programs are not so well-behaved, 
and consequently you'll lock out a large fraction of existing programs from 
being %run from IPython.  And from a user's POV, this will even appear to be a 
regression, even if previous support for that was buggy - there *was* support 
for it.

I'd say not looking at other program's deficiencies, but closing the eyes and 
adding some proper hack would be much more in the spirit of IPython.


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