Deprecate support for 3rd-party backends without set_hatch_color.

anntzer · anntzer · commit 31a6682c86d7 · 2018-07-23T00:05:35.000+02:00
Inheriting from GraphicsContextBase to get a stub definition of
set_hatch_color (or providing your own stub) is really not that much to
ask, I believe.
diff --git a/doc/api/next_api_changes/2018-07-22-AL-deprecations.rst b/doc/api/next_api_changes/2018-07-22-AL-deprecations.rst
@@ -0,0 +1,7 @@
+Deprecations
+------------
+
+Support for custom backends that do not provide a ``set_hatch_color`` method is
+deprecated.  We suggest that custom backends let their ``GraphicsContext``
+class inherit from `GraphicsContextBase`, to at least provide stubs for all
+required methods.
diff --git a/lib/matplotlib/collections.py b/lib/matplotlib/collections.py
@@ -271,8 +271,10 @@ def draw(self, renderer):
                 gc.set_hatch_color(self._hatch_color)
             except AttributeError:
                 # if we end up with a GC that does not have this method
-                warnings.warn("Your backend does not support setting the "
-                              "hatch color.")
+                cbook.warn_deprecated(
+                    "3.1", "Your backend does not support setting the hatch "
+                    "color; such backends will become unsupported in "
+                    "Matplotlib 3.3.")
 
         if self.get_sketch_params() is not None:
             gc.set_sketch_params(*self.get_sketch_params())
diff --git a/lib/matplotlib/patches.py b/lib/matplotlib/patches.py
@@ -515,8 +515,10 @@ def draw(self, renderer):
                 gc.set_hatch_color(self._hatch_color)
             except AttributeError:
                 # if we end up with a GC that does not have this method
-                warnings.warn(
-                    "Your backend does not support setting the hatch color.")
+                cbook.warn_deprecated(
+                    "3.1", "Your backend does not support setting the hatch "
+                    "color; such backends will become unsupported in "
+                    "Matplotlib 3.3.")
 
         if self.get_sketch_params() is not None:
             gc.set_sketch_params(*self.get_sketch_params())
@@ -4285,8 +4287,10 @@ def draw(self, renderer):
                     gc.set_hatch_color(self._hatch_color)
                 except AttributeError:
                     # if we end up with a GC that does not have this method
-                    warnings.warn("Your backend does not support setting the "
-                                  "hatch color.")
+                    cbook.warn_deprecated(
+                        "3.1", "Your backend does not support setting the "
+                        "hatch color; such backends will become unsupported "
+                        "in Matplotlib 3.3.")
 
         if self.get_sketch_params() is not None:
             gc.set_sketch_params(*self.get_sketch_params())
