Adding more documentation of inputhook.py

IPython/lib/inputhook.py

@@ -1,286 +1,292 b''
 #!/usr/bin/env python
 # encoding: utf-8
 """
 Inputhook management for GUI event loop integration.
 """
 
 #-----------------------------------------------------------------------------
 #  Copyright (C) 2008-2009  The IPython Development Team
 #
 #  Distributed under the terms of the BSD License.  The full license is in
 #  the file COPYING, distributed as part of this software.
 #-----------------------------------------------------------------------------
 
 #-----------------------------------------------------------------------------
 # Imports
 #-----------------------------------------------------------------------------
 
 import ctypes
 import sys
 
 #-----------------------------------------------------------------------------
 # Code
 #-----------------------------------------------------------------------------
 
 def _dummy_mainloop(*args, **kw):
     pass
 
 
 class InputHookManager(object):
     """Manage PyOS_InputHook for different GUI toolkits.
 
     This class installs various hooks under ``PyOSInputHook`` to handle
     GUI event loop integration.
     """
     
     def __init__(self):
         self.PYFUNC = ctypes.PYFUNCTYPE(ctypes.c_int)
         self._apps = {}
         self._reset()
 
     def _reset(self):
         self._callback_pyfunctype = None
         self._callback = None
         self._installed = False
         self._current_gui = None
 
     def _hijack_wx(self):
+        """Hijack the wx mainloop so a user calling it won't cause badness."""
         import wx
         if hasattr(wx, '_core_'): core = getattr(wx, '_core_')
         elif hasattr(wx, '_core'): core = getattr(wx, '_core')
         else: raise AttributeError('Could not find wx core module')
         orig_mainloop = core.PyApp_MainLoop
         core.PyApp_MainLoop = _dummy_mainloop
         return orig_mainloop
 
     def _hijack_qt4(self):
+        """Hijack the qt4 mainloop so a user calling it won't cause badness."""
         from PyQt4 import QtGui, QtCore
         orig_mainloop = QtGui.qApp.exec_
         QtGui.qApp.exec_ = _dummy_mainloop
         QtGui.QApplication.exec_ = _dummy_mainloop
         QtCore.QCoreApplication.exec_ = _dummy_mainloop
         return orig_mainloop
 
     def _hijack_gtk(self):
+        """Hijack the gtk mainloop so a user calling it won't cause badness."""
         import gtk
         orig_mainloop = gtk.main
         gtk.mainloop = _dummy_mainloop
         gtk.main = _dummy_mainloop
         return orig_mainloop
 
     def _hijack_tk(self):
+        """Hijack the tk mainloop so a user calling it won't cause badness."""
         import Tkinter
         Tkinter.Misc.mainloop = _dummy_mainloop
         Tkinter.mainloop = _dummy_mainloop
 
     def get_pyos_inputhook(self):
-        """Return the current PyOS_InputHook as a ctypes.c_void_p.
-        """
+        """Return the current PyOS_InputHook as a ctypes.c_void_p."""
         return ctypes.c_void_p.in_dll(ctypes.pythonapi,"PyOS_InputHook")
 
     def get_pyos_inputhook_as_func(self):
-        """Return the current PyOS_InputHook as a ctypes.PYFUNCYPE.
-        """
+        """Return the current PyOS_InputHook as a ctypes.PYFUNCYPE."""
         return self.PYFUNC.in_dll(ctypes.pythonapi,"PyOS_InputHook")
 
     def set_inputhook(self, callback):
-        """Set PyOS_InputHook to callback and return the previous one.
-        """
+        """Set PyOS_InputHook to callback and return the previous one."""
         self._callback = callback
         self._callback_pyfunctype = self.PYFUNC(callback)
         pyos_inputhook_ptr = self.get_pyos_inputhook()
         original = self.get_pyos_inputhook_as_func()
         pyos_inputhook_ptr.value = \
             ctypes.cast(self._callback_pyfunctype, ctypes.c_void_p).value
         self._installed = True
         return original
 
     def clear_inputhook(self):
-        """Set PyOS_InputHook to NULL and return the previous one.
-        """
+        """Set PyOS_InputHook to NULL and return the previous one."""
         pyos_inputhook_ptr = self.get_pyos_inputhook()
         original = self.get_pyos_inputhook_as_func()
         pyos_inputhook_ptr.value = ctypes.c_void_p(None).value
         self._reset()
         return original
 
     def clear_app_refs(self, gui=None):
         """Clear IPython's internal reference to an application instance.
 
+        Whenever we create an app for a user on qt4 or wx, we hold a
+        reference to the app.  This is needed because in some cases bad things
+        can happen if a user doesn't hold a reference themselves.  This
+        method is provided to clear the references we are holding.
+
         Parameters
         ----------
         gui : None or str
             If None, clear all app references.  If ('wx', 'qt4') clear
             the app for that toolkit.  References are not held for gtk or tk
             as those toolkits don't have the notion of an app.
         """
         if gui is None:
             self._apps = {}
         elif self._apps.has_key(gui):
             del self._apps[gui]
 
     def enable_wx(self, app=False):
         """Enable event loop integration with wxPython.
 
         Parameters
         ----------
         app : bool
             Create a running application object or not.
 
         Notes
         -----
-        This methods sets the PyOS_InputHook for wxPython, which allows
+        This methods sets the ``PyOS_InputHook`` for wxPython, which allows
         the wxPython to integrate with terminal based applications like
         IPython.
-        
-        Once this has been called, you can use wx interactively by doing::
-        
-            >>> import wx
-            >>> app = wx.App(redirect=False, clearSigInt=False)
-        
+
+        If ``app`` is True, we create an :class:`wx.App` as follows::
+
+            import wx
+            app = wx.App(redirect=False, clearSigInt=False)
+
         Both options this constructor are important for things to work
         properly in an interactive context.
-        
-        But, *don't start the event loop*.  That is handled automatically by
-        PyOS_InputHook.
+
+        But, we first check to see if an application has already been 
+        created.  If so, we simply return that instance.
         """
         from IPython.lib.inputhookwx import inputhook_wx
         self.set_inputhook(inputhook_wx)
         self._current_gui = 'wx'
         self._hijack_wx()
         if app:
             import wx
             app = wx.GetApp()
             if app is None:
                 app = wx.App(redirect=False, clearSigInt=False)
                 self._apps['wx'] = app
             return app
 
     def disable_wx(self):
         """Disable event loop integration with wxPython.
-        
+
         This merely sets PyOS_InputHook to NULL.
         """
         self.clear_inputhook()
 
     def enable_qt4(self, app=False):
         """Enable event loop integration with PyQt4.
         
         Parameters
         ----------
         app : bool
             Create a running application object or not.
 
         Notes
         -----
-        This methods sets the PyOS_InputHook for wxPython, which allows
+        This methods sets the PyOS_InputHook for PyQt4, which allows
         the PyQt4 to integrate with terminal based applications like
         IPython.
-        
-        Once this has been called, you can simply create a QApplication and
-        use it.  But, *don't start the event loop*.  That is handled
-        automatically by PyOS_InputHook.
+
+        If ``app`` is True, we create an :class:`QApplication` as follows::
+
+            from PyQt4 import QtCore
+            app = QtGui.QApplication(sys.argv)
+
+        But, we first check to see if an application has already been 
+        created.  If so, we simply return that instance.
         """
         from PyQt4 import QtCore
         # PyQt4 has had this since 4.3.1.  In version 4.2, PyOS_InputHook
         # was set when QtCore was imported, but if it ever got removed,
         # you couldn't reset it.  For earlier versions we can
         # probably implement a ctypes version.
         try:
             QtCore.pyqtRestoreInputHook()
         except AttributeError:
             pass
         self._current_gui = 'qt4'
         self._hijack_qt4()
         if app:
             from PyQt4 import QtGui
             app = QtGui.QApplication.instance()
             if app is None:
                 app = QtGui.QApplication(sys.argv)
                 self._apps['qt4'] = app
             return app
 
     def disable_qt4(self):
         """Disable event loop integration with PyQt4.
-        
+
         This merely sets PyOS_InputHook to NULL.
         """
         self.clear_inputhook()
 
     def enable_gtk(self, app=False):
         """Enable event loop integration with PyGTK.
 
         Parameters
         ----------
         app : bool
-            Create a running application object or not.
+            Create a running application object or not.  Because gtk does't
+            have an app class, this does nothing.
 
         Notes
         -----
         This methods sets the PyOS_InputHook for PyGTK, which allows
         the PyGTK to integrate with terminal based applications like
         IPython.
-        
-        Once this has been called, you can simple create PyGTK objects and
-        use them.  But, *don't start the event loop*.  That is handled
-        automatically by PyOS_InputHook.
         """
         import gtk
         try:
             gtk.set_interactive(True)
             self._current_gui = 'gtk'
         except AttributeError:
             # For older versions of gtk, use our own ctypes version
             from IPython.lib.inputhookgtk import inputhook_gtk
             self.set_inputhook(inputhook_gtk)
             self._current_gui = 'gtk'
         self._hijack_gtk()
 
     def disable_gtk(self):
         """Disable event loop integration with PyGTK.
         
         This merely sets PyOS_InputHook to NULL.
         """
         self.clear_inputhook()
 
     def enable_tk(self, app=False):
         """Enable event loop integration with Tk.
 
         Parameters
         ----------
         app : bool
             Create a running application object or not.
 
         Notes
         -----
         Currently this is a no-op as creating a :class:`Tkinter.Tk` object 
         sets ``PyOS_InputHook``.
         """
         self._current_gui = 'tk'
         self._hijack_tk()
 
     def disable_tk(self):
         """Disable event loop integration with Tkinter.
         
         This merely sets PyOS_InputHook to NULL.
         """
         self.clear_inputhook()
 
     def current_gui(self):
         """Return a string indicating the currently active GUI or None."""
         return self._current_gui
 
 inputhook_manager = InputHookManager()
 
 enable_wx = inputhook_manager.enable_wx
 disable_wx = inputhook_manager.disable_wx
 enable_qt4 = inputhook_manager.enable_qt4
 disable_qt4 = inputhook_manager.disable_qt4
 enable_gtk = inputhook_manager.enable_gtk
 disable_gtk = inputhook_manager.disable_gtk
 enable_tk = inputhook_manager.enable_tk
 disable_tk = inputhook_manager.disable_tk
 clear_inputhook = inputhook_manager.clear_inputhook
 set_inputhook = inputhook_manager.set_inputhook
 current_gui = inputhook_manager.current_gui
 clear_app_refs = inputhook_manager.clear_app_refs