Merged revisions 5360 via svnmerge from

jdh2358 · jdh2358 · commit c81cb87c96e3 · 2008-06-02T17:13:01.000Z
https://matplotlib.svn.sourceforge.net/svnroot/matplotlib/branches/v0_91_maint ........ r5360 | jdh2358 | 2008-06-02 10:06:41 -0500 (Mon, 02 Jun 2008) | 1 line added switch_backend bugfix from sf patch 1979402 ........ svn path=/trunk/matplotlib/; revision=5361
diff --git a/lib/matplotlib/__init__.py b/lib/matplotlib/__init__.py
@@ -740,7 +740,7 @@ def rcdefaults():
 or matplotlib.backends is imported for the first time.
 """
 
-def use(arg):
+def use(arg, warn=True):
     """
     Set the matplotlib backend to one of the known backends.
 
@@ -752,12 +752,17 @@ def use(arg):
 
     will specify a default of pdf output generated by Cairo.
 
-    Note: this function must be called *before* importing pylab
-    for the first time; or, if you are not using pylab, it must
-    be called before importing matplotlib.backends.
+    Note: this function must be called *before* importing pylab for
+    the first time; or, if you are not using pylab, it must be called
+    before importing matplotlib.backends.  If warn is True, a warning
+    is issued if you try and callthis after pylab or pyplot have been
+    loaded.  In certain black magic use cases, eg
+    pyplot.switch_backends, we are doing the reloading necessary to
+    make the backend switch work (in some cases, eg pure image
+    backends) so one can set warn=False to supporess the warnings
     """
     if 'matplotlib.backends' in sys.modules:
-        warnings.warn(_use_error_msg)
+        if warn: warnings.warn(_use_error_msg)
     be_parts = arg.split('.')
     name = validate_backend(be_parts[0])
     rcParams['backend'] = name
diff --git a/lib/matplotlib/pyplot.py b/lib/matplotlib/pyplot.py
@@ -52,10 +52,10 @@ def switch_backend(newbackend):
     """
     close('all')
     global new_figure_manager, draw_if_interactive, show
-    matplotlib.use(newbackend)
-    reload(backends)
-    from backends import new_figure_manager, draw_if_interactive, show
-
+    matplotlib.use(newbackend, warn=False)
+    reload(matplotlib.backends)
+    from matplotlib.backends import pylab_setup
+    new_figure_manager, draw_if_interactive, show = pylab_setup()
 
 
 def isinteractive():
