Hi folks, the message below is an important discussion on which we'd like feedback/ideas both from Enthought.traits experts and matplotlib ones. It would be great if we could keep things in one list, so it seems most sensible to hold the discussion in the ipython-dev list, but this is a heads-up in case one of you is interested but may not monitor ipython-dev.
Thanks! f ---------- Forwarded message ---------- From: Brian Granger <ellisonbg....@gmail.com> Date: Tue, Feb 9, 2010 at 11:59 PM Subject: [IPython-dev] GUI support: conflicts between IPython 0.11 and Matplotlib/ETS To: IPython Development list <ipython-...@scipy.org> Hello all, As many of you know, we have been working hard on IPython 0.11. One of the big new features of 0.11 is a refactored integration with GUI event loops. We are very excited about this as it is much more stable and add new capabilities, like being able to enable pylab *after* starting IPython (it is a magic: %pylab). BUT, as Fernando and I have started to use the IPython 0.11 alpha for our daily work, we have found some subtle issue with IPython 0.11 and the current versions of matplotlib and Enthought tool suite (traits, chaco, mayavi). All of these packages rely on IPython's previous way of handling GUI integration. Because of this, current versions of matplotlib and ets don't work fully with IPython 0.11. In some cases, they work OK, but there are a whole class of bugs that keep popping up. We don't want to release IPython 0.11 until these issues are resolved. All of these bugs are related to a few aspects of creating the main GUI app objects and starting event loops. We think we understand the issues, but we will need to work with the devs of matplotlib and ets to decide on how we all want to handle these things. Here is where we are at... Current situation ============= Both matplotlib and ets have code that tries to: * See what GUI toolkit is being used * Get the global App object if it already exists, if not create it. * See if the main loop is running, if not possibly start it. All of this logic makes many assumptions about how IPython affects the answers to these questions. Because IPython's GUI support has changed in significant ways, current matplotlib and ets make incorrect decisions about these issues (such as trying to start the event loop a second time, creating a second main App ojbect, etc.) under IPython 0.11. This leads to crashes... Description of GUI support in 0.11 ========================== IPython allows GUI event loops to be run in an interactive IPython session. This is done using Python's PyOS_InputHook hook which Python calls when the :func:`raw_input` function is called and is waiting for user input. IPython has versions of this hook for wx, pyqt4 and pygtk. When the inputhook is called, it iterates the GUI event loop until a user starts to type again. When the user stops typing, the event loop iterates again. This is how tk works. When a GUI program is used interactively within IPython, the event loop of the GUI should *not* be started. This is because, the PyOS_Inputhook itself is responsible for iterating the GUI event loop. IPython has facilities for installing the needed input hook for each GUI toolkit and for creating the needed main GUI application object. Usually, these main application objects should be created only once and for some GUI toolkits, special options have to be passed to the application object to enable it to function properly in IPython. What we need to decide =================== We need to answer the following questions: * Who is responsible for creating the main GUI application object, IPython or third parties (matplotlib, enthought.traits, etc.)? * What is the proper way for third party code to detect if a GUI application object has already been created? If one has been created, how should the existing instance be retrieved? * In a GUI application object has been created, how should third party code detect if the GUI event loop is running. It is not sufficient to call the relevant function methods in the GUI toolkits (like ``IsMainLoopRunning``) because those don't know if the GUI event loop is running through the input hook. * We might need a way for third party code to determine if it is running in IPython or not. Currently, the only way of running GUI code in IPython is by using the input hook, but eventually, GUI based versions of IPython will allow the GUI event loop in the more traditional manner. We will need a way for third party code to distinguish between these two cases. Thanks for participating in this discussion! Cheers, Brian _______________________________________________ IPython-dev mailing list ipython-...@scipy.org http://mail.scipy.org/mailman/listinfo/ipython-dev ------------------------------------------------------------------------------ SOLARIS 10 is the OS for Data Centers - provides features such as DTrace, Predictive Self Healing and Award Winning ZFS. Get Solaris 10 NOW http://p.sf.net/sfu/solaris-dev2dev _______________________________________________ Matplotlib-devel mailing list Matplotlib-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/matplotlib-devel
