Reuse the noninteractivity warning from Figure.show in _Backend.show.

anntzer · anntzer · commit 6cf845070a0d · 2018-05-24T23:01:28.000-07:00
Currently, the warning message "Matplotlib is currently using ..., which
is a non-GUI backend, so cannot show the figure" and the (minor)
associated logic (of catching NonGuiException) is duplicated between
Figure.show and _Backend.show.  Make the latter use the former, to
deduplicate it.
diff --git a/lib/matplotlib/backend_bases.py b/lib/matplotlib/backend_bases.py
@@ -185,14 +185,8 @@ def show(cls, block=None):
         if not managers:
             return
         for manager in managers:
-            try:
-                manager.show()
-            except NonGuiException:
-                warnings.warn(
-                    ('matplotlib is currently using %s, which is a ' +
-                     'non-GUI backend, so cannot show the figure.')
-                    % get_backend())
-                return
+            # Emits a warning if the backend is non-interactive.
+            manager.canvas.figure.show()
         if cls.mainloop is None:
             return
         if block is None:
diff --git a/lib/matplotlib/figure.py b/lib/matplotlib/figure.py
@@ -439,10 +439,9 @@ def show(self, warn=True):
             except NonGuiException:
                 pass
         if warn:
-            warnings.warn(
-                ('matplotlib is currently using %s, which is a ' +
-                 'non-GUI backend, so cannot show the figure.')
-                % get_backend())
+            warnings.warn('Matplotlib is currently using %s, which is a '
+                          'non-GUI backend, so cannot show the figure.'
+                          % get_backend())
 
     def _get_axes(self):
         return self._axstack.as_list()
diff --git a/lib/matplotlib/tests/test_backend_bases.py b/lib/matplotlib/tests/test_backend_bases.py
@@ -69,13 +69,11 @@ def test_non_gui_warning():
     with pytest.warns(UserWarning) as rec:
         plt.show()
         assert len(rec) == 1
-        assert 'matplotlib is currently using pdf, ' \
-               'which is a non-GUI backend' \
-               in str(rec[0].message)
+        assert ('Matplotlib is currently using pdf, which is a non-GUI backend'
+                in str(rec[0].message))
 
     with pytest.warns(UserWarning) as rec:
         plt.gcf().show()
         assert len(rec) == 1
-        assert 'matplotlib is currently using pdf, ' \
-               'which is a non-GUI backend' \
-               in str(rec[0].message)
+        assert ('Matplotlib is currently using pdf, which is a non-GUI backend'
+                in str(rec[0].message))
