[IPython-dev] Qt api selection re. ipython and matplotlib

[Darren Dale]

On Tue, Jul 5, 2011 at 2:22 AM, Eric Firing <efiring at hawaii.edu> wrote:
> On 07/04/2011 06:51 PM, MinRK wrote:
>>
>> On Mon, Jul 4, 2011 at 20:57, Eric Firing<efiring at hawaii.edu>  wrote:
>>> If I remove the version-setting from qt.py, then ipython still works
>>> with mpl and PyQt4 via "ipython pylab=qt", but it does not work with
>>> qtconsole or with PySide.
>>
>> I don't think we are going to rewrite the whole qtconsole to support
>> version 1 for 0.11 this week.  What we can do is change the default
>> behavior in qt_for_kernel,
>>
>> (https://github.com/ipython/ipython/blob/master/IPython/external/qt_for_kernel.py)
>> which is where code that interacts with other applications gets
>> imported.  Currently, we use our v2 import unless matplotlib<= 1.0.1
>> is detected.  However, we can change that default to be more
>> conservative.  User code (e.g. matplotlib code, integration with other
>> apps) is not in the same process as the QtConsole, so we can have v1
>> code in the kernel with v2 in the frontend.

Good point.

> If ipython and mpl have to be synchronized, and if we want to be able to
> choose to use pyside or pyqt4, then I think we need more than a change in
> the ipython default.  It looks like this calls for yet another pesky
> rcParams entry in mpl.  Then that can be used for figuring out what to
> import in both matplotlib and ipython.  The default, if there is no rcParams
> entry, would be PyQt4 with the platform default API version.
>
> Darren, does this sound like a solution that would work for you?

If ipython changes its qt_for_kernel to not set the api level, then it
seems to me that either the environment variable approach or the
rcParams approach will work for pylab/pyplot. The rcParams approach is
a little awkward for folks using the OO interface, but it looks like
it would work. You mentioned that it does not work with the ipython
console and pyside though, what doesn't work?