use get_ipython API function, not builtin injection, to detect IPython.

IPython/kernel/zmq/pylab/backend_inline.py

@@ -1,153 +1,151 b''
 """A matplotlib backend for publishing figures via display_data"""
 #-----------------------------------------------------------------------------
 #       Copyright (C) 2011 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
 #-----------------------------------------------------------------------------
 from __future__ import print_function
 
 # Third-party imports
 import matplotlib
 from matplotlib.backends.backend_agg import FigureCanvasAgg
 from matplotlib._pylab_helpers import Gcf
 
 # Local imports
 from IPython.core.getipython import get_ipython
 from IPython.core.display import display
 
 from .config import InlineBackend
 
 #-----------------------------------------------------------------------------
 # Functions
 #-----------------------------------------------------------------------------
 
 def show(close=None):
     """Show all figures as SVG/PNG payloads sent to the IPython clients.
 
     Parameters
     ----------
     close : bool, optional
       If true, a ``plt.close('all')`` call is automatically issued after
       sending all the figures. If this is set, the figures will entirely
       removed from the internal list of figures.
     """
     if close is None:
         close = InlineBackend.instance().close_figures
     try:
         for figure_manager in Gcf.get_all_fig_managers():
             display(figure_manager.canvas.figure)
     finally:
         show._to_draw = []
         if close:
             matplotlib.pyplot.close('all')
 
 
 # This flag will be reset by draw_if_interactive when called
 show._draw_called = False
 # list of figures to draw when flush_figures is called
 show._to_draw = []
 
 
 def draw_if_interactive():
     """
     Is called after every pylab drawing command
     """
     # signal that the current active figure should be sent at the end of
     # execution.  Also sets the _draw_called flag, signaling that there will be
     # something to send.  At the end of the code execution, a separate call to
     # flush_figures() will act upon these values
     manager = Gcf.get_active()
     if manager is None:
         return
     fig = manager.canvas.figure
 
     # Hack: matplotlib FigureManager objects in interacive backends (at least
     # in some of them) monkeypatch the figure object and add a .show() method
     # to it.  This applies the same monkeypatch in order to support user code
     # that might expect `.show()` to be part of the official API of figure
     # objects.
     # For further reference:
     # https://github.com/ipython/ipython/issues/1612
     # https://github.com/matplotlib/matplotlib/issues/835
     
     if not hasattr(fig, 'show'):
         # Queue up `fig` for display
         fig.show = lambda *a: display(fig)
 
     # If matplotlib was manually set to non-interactive mode, this function
     # should be a no-op (otherwise we'll generate duplicate plots, since a user
     # who set ioff() manually expects to make separate draw/show calls).
     if not matplotlib.is_interactive():
         return
 
     # ensure current figure will be drawn, and each subsequent call
     # of draw_if_interactive() moves the active figure to ensure it is
     # drawn last
     try:
         show._to_draw.remove(fig)
     except ValueError:
         # ensure it only appears in the draw list once
         pass
     # Queue up the figure for drawing in next show() call
     show._to_draw.append(fig)
     show._draw_called = True
 
 
 def flush_figures():
     """Send all figures that changed
 
     This is meant to be called automatically and will call show() if, during
     prior code execution, there had been any calls to draw_if_interactive.
     
     This function is meant to be used as a post_execute callback in IPython,
     so user-caused errors are handled with showtraceback() instead of being
     allowed to raise.  If this function is not called from within IPython,
     then these exceptions will raise.
     """
     if not show._draw_called:
         return
     
     if InlineBackend.instance().close_figures:
         # ignore the tracking, just draw and close all figures
         try:
             return show(True)
         except Exception as e:
             # safely show traceback if in IPython, else raise
-            try:
-                get_ipython
-            except NameError:
+            ip = get_ipython()
+            if ip is None:
                 raise e
             else:
-                get_ipython().showtraceback()
+                ip.showtraceback()
                 return
     try:
         # exclude any figures that were closed:
         active = set([fm.canvas.figure for fm in Gcf.get_all_fig_managers()])
         for fig in [ fig for fig in show._to_draw if fig in active ]:
             try:
                 display(fig)
             except Exception as e:
                 # safely show traceback if in IPython, else raise
-                try:
-                    get_ipython
-                except NameError:
+                ip = get_ipython()
+                if ip is None:
                     raise e
                 else:
-                    get_ipython().showtraceback()
-                    break
+                    ip.showtraceback()
+                    return
     finally:
         # clear flags for next round
         show._to_draw = []
         show._draw_called = False
 
 
 # Changes to matplotlib in version 1.2 requires a mpl backend to supply a default
 # figurecanvas. This is set here to a Agg canvas
 # See https://github.com/matplotlib/matplotlib/pull/1125
 FigureCanvas = FigureCanvasAgg