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=========================
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IPython GUI Support Notes
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=========================
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IPython allows GUI event loops to be run in an interactive IPython session.
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This is done using Python's PyOS_InputHook hook which Python calls
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when the :func:`raw_input` function is called and waiting for user input.
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IPython has versions of this hook for wx, pyqt4 and pygtk.
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When a GUI program is used interactively within IPython, the event loop of
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the GUI should *not* be started. This is because, the PyOS_Inputhook itself
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is responsible for iterating the GUI event loop.
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IPython has facilities for installing the needed input hook for each GUI
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toolkit and for creating the needed main GUI application object. Usually,
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these main application objects should be created only once and for some
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GUI toolkits, special options have to be passed to the application object
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to enable it to function properly in IPython.
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We need to answer the following questions:
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* Who is responsible for creating the main GUI application object, IPython
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or third parties (matplotlib, enthought.traits, etc.)?
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* What is the proper way for third party code to detect if a GUI application
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object has already been created? If one has been created, how should
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the existing instance be retrieved?
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* In a GUI application object has been created, how should third party code
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detect if the GUI event loop is running. It is not sufficient to call the
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relevant function methods in the GUI toolkits (like ``IsMainLoopRunning``)
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because those don't know if the GUI event loop is running through the
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input hook.
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* We might need a way for third party code to determine if it is running
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in IPython or not. Currently, the only way of running GUI code in IPython
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is by using the input hook, but eventually, GUI based versions of IPython
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will allow the GUI event loop in the more traditional manner. We will need
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a way for third party code to distinguish between these two cases.
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Here is some sample code I have been using to debug this issue::
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from matplotlib import pyplot as plt
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from enthought.traits import api as traits
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class Foo(traits.HasTraits):
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a = traits.Float()
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f = Foo()
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f.configure_traits()
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plt.plot(range(10))
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