Added --gui to match %gui use, better docs and behavior for %pylab code.

Now both %gui and %pylab have identical syntax if used at startup as --gui
and --pylab.  This can be useful to people setting up aliases or other
shell-based support.

Also cleaned up %pylab so it doesn't pollute the output of %who with all
loaded symbols.

IPython/core/ipapp.py

@@ -244,22 +244,39 b' cl_args = ('
         action='store_true', dest='Global.force_interact', default=NoConfigDefault,
         help="If running code from the command line, become interactive afterwards.")
     ),
+
+    # Options to start with GUI control enabled from the beginning
+    (('--gui',), dict(
+        type=str, dest='Global.gui', default=NoConfigDefault,
+        help="Enable GUI event loop integration ('qt', 'wx', 'gtk').",
+        metavar='gui-mode')
+    ),
+
+    (('--pylab',), dict(
+        type=str, dest='Global.pylab', default=NoConfigDefault,
+        nargs='?', const='auto', metavar='gui-mode',
+        help="Pre-load matplotlib and numpy for interactive use. "+
+        "If no value is given, the gui backend is matplotlib's, else use "+
+        "one of:  ['tk', 'qt', 'wx', 'gtk'].")
+    ),
+    
+    # Legacy GUI options.  Leave them in for backwards compatibility, but the
+    # 'thread' names are really a misnomer now.
     (('--wthread','-wthread'), dict(
         action='store_true', dest='Global.wthread', default=NoConfigDefault,
-        help="Enable wxPython event loop integration.")
+        help="Enable wxPython event loop integration "+
+             "(DEPRECATED, use --gui wx)")
     ),
     (('--q4thread','--qthread','-q4thread','-qthread'), dict(
         action='store_true', dest='Global.q4thread', default=NoConfigDefault,
-        help="Enable Qt4 event loop integration. Qt3 is no longer supported.")
+        help="Enable Qt4 event loop integration. Qt3 is no longer supported. "+
+             "(DEPRECATED, use --gui qt)")
     ),
     (('--gthread','-gthread'), dict(
         action='store_true', dest='Global.gthread', default=NoConfigDefault,
-        help="Enable GTK event loop integration.")
+        help="Enable GTK event loop integration. "+
+             "(DEPRECATED, use --gui gtk)")
     ),
-    (('--pylab',), dict(
-        action='store_true', dest='Global.pylab', default=NoConfigDefault,
-        help="Pre-load matplotlib and numpy for interactive use.")
-    )
 )
 
 
@@ -298,6 +315,7 b' class IPythonApp(Application):'
         super(IPythonApp, self).create_default_config()
         # Eliminate multiple lookups
         Global = self.default_config.Global
+
         # Set all default values
         Global.display_banner = True
         
@@ -312,13 +330,18 b' class IPythonApp(Application):'
         Global.interact = True
 
         # No GUI integration by default
-        Global.wthread = False
-        Global.q4thread = False
-        Global.gthread = False
-
+        Global.gui = False
         # Pylab off by default
         Global.pylab = False
 
+        # Deprecated versions of gui support that used threading, we support
+        # them just for bacwards compatibility as an alternate spelling for
+        # '--gui X'
+        Global.qthread = False
+        Global.q4thread = False
+        Global.wthread = False
+        Global.gthread = False
+
     def create_command_line_config(self):
         """Create and return a command line config loader."""
         return IPythonAppCLConfigLoader(
@@ -415,32 +438,41 b' class IPythonApp(Application):'
         Global = self.master_config.Global
 
         # Select which gui to use
-        if Global.wthread:
+        if Global.gui:
+            gui = Global.gui
+        # The following are deprecated, but there's likely to be a lot of use
+        # of this form out there, so we might as well support it for now.  But
+        # the --gui option above takes precedence.
+        elif Global.wthread:
             gui = inputhook.GUI_WX
-        elif Global.q4thread:
+        elif Global.qthread:
             gui = inputhook.GUI_QT
         elif Global.gthread:
             gui = inputhook.GUI_GTK
         else:
             gui = None
 
+        # Using --pylab will also require gui activation, though which toolkit
+        # to use may be chosen automatically based on mpl configuration.
         if Global.pylab:
             activate = self.shell.enable_pylab
+            if Global.pylab == 'auto':
+                gui = None
+            else:
+                gui = Global.pylab
         else:
             # Enable only GUI integration, no pylab
             activate = inputhook.enable_gui
 
         if gui or Global.pylab:
             try:
-                m = "Enabling GUI event loop integration, toolkit=%s, pylab=%s"\
-                    % (gui, Global.pylab)
-                self.log.info(m)
+                self.log.info("Enabling GUI event loop integration, "
+                              "toolkit=%s, pylab=%s" % (gui, Global.pylab) )
                 activate(gui)
             except:
                 self.log.warn("Error in enabling GUI event loop integration:")
                 self.shell.showtraceback()
 
-
     def _load_extensions(self):
         """Load all IPython extensions in Global.extensions.
 

IPython/core/iplib.py

@@ -827,7 +827,7 b' class InteractiveShell(Component, Magic):'
         # An auxiliary namespace that checks what parts of the user_ns were
         # loaded at startup, so we can list later only variables defined in
         # actual interactive use.  Since it is always a subset of user_ns, it
-        # doesn't need to be seaparately tracked in the ns_table
+        # doesn't need to be separately tracked in the ns_table.
         self.user_config_ns = {}
 
         # A namespace to keep track of internal data structures to prevent
@@ -2451,13 +2451,36 b' class InteractiveShell(Component, Magic):'
     #-------------------------------------------------------------------------
 
     def enable_pylab(self, gui=None):
+        """Activate pylab support at runtime.
+
+        This turns on support for matplotlib, preloads into the interactive
+        namespace all of numpy and pylab, and configures IPython to correcdtly
+        interact with the GUI event loop.  The GUI backend to be used can be
+        optionally selected with the optional :param:`gui` argument.
+
+        Parameters
+        ----------
+        gui : optional, string
+
+          If given, dictates the choice of matplotlib GUI backend to use
+          (should be one of IPython's supported backends, 'tk', 'qt', 'wx' or
+          'gtk'), otherwise we use the default chosen by matplotlib (as
+          dictated by the matplotlib build-time options plus the user's
+          matplotlibrc configuration file).
         """
-        """
-        gui = pylab_activate(self.user_ns, gui)
+        # We want to prevent the loading of pylab to pollute the user's
+        # namespace as shown by the %who* magics, so we execute the activation
+        # code in an empty namespace, and we update *both* user_ns and
+        # user_config_ns with this information.
+        ns = {}
+        gui = pylab_activate(ns, gui)
+        self.user_ns.update(ns)
+        self.user_config_ns.update(ns)
+        # Now we must activate the gui pylab wants to use, and fix %run to take
+        # plot updates into account
         enable_gui(gui)
         self.magic_run = self._pylab_magic_run
 
-
     #-------------------------------------------------------------------------
     # Things related to IPython exiting
     #-------------------------------------------------------------------------

IPython/core/prefilter.py

@@ -845,16 +845,11 b' class AutoHandler(PrefilterHandler):'
         pre     = line_info.pre
         continue_prompt = line_info.continue_prompt
         obj = line_info.ofind(self)['obj']
-
         #print 'pre <%s> ifun <%s> rest <%s>' % (pre,ifun,the_rest)  # dbg
 
         # This should only be active for single-line input!
         if continue_prompt:
-            # XXX - Ugly hack!  We are breaking on multiline input and I'm out
-            # of time tonight to disentangle the component hirerarchy issue
-            # here... Fix this more cleanly later.
             self.shell.log(line,line,continue_prompt)
-            
             return line
 
         force_auto = isinstance(obj, IPyAutocall)