Rework deprecation mechanism.

anntzer · anntzer · commit fc34d69f010e · 2020-10-07T11:55:38.000+02:00
diff --git a/lib/matplotlib/cbook/deprecation.py b/lib/matplotlib/cbook/deprecation.py
@@ -465,7 +465,8 @@ def _deprecate_method_override(method, obj, *, allow_empty=False, **kwargs):
         can always use ``__class__`` to refer to the class that is currently
         being defined.
     obj
-        An object of the class where *method* is defined.
+        Either an object of the class where *method* is defined, or a subclass
+        of that class.
     allow_empty : bool, default: False
         Whether to allow overrides by "empty" methods without emitting a
         warning.
@@ -478,15 +479,19 @@ def empty(): pass
     def empty_with_docstring(): """doc"""
 
     name = method.__name__
-    bound_method = getattr(obj, name)
-    if (bound_method != method.__get__(obj)
+    bound_child = getattr(obj, name)
+    bound_base = (
+        method  # If obj is a class, then we need to use unbound methods.
+        if isinstance(bound_child, type(empty)) and isinstance(obj, type)
+        else method.__get__(obj))
+    if (bound_child != bound_base
             and (not allow_empty
-                 or (getattr(getattr(bound_method, "__code__", None),
+                 or (getattr(getattr(bound_child, "__code__", None),
                              "co_code", None)
                      not in [empty.__code__.co_code,
                              empty_with_docstring.__code__.co_code]))):
         warn_deprecated(**{"name": name, "obj_type": "method", **kwargs})
-        return bound_method
+        return bound_child
     return None
 
 
diff --git a/lib/matplotlib/patches.py b/lib/matplotlib/patches.py
@@ -1955,7 +1955,10 @@ def transmute(self, x0, y0, width, height, mutation_size):
         # This can go away once the deprecation period elapses, leaving _Base
         # as a fully abstract base class just providing docstrings, no logic.
         def __init_subclass__(cls):
-            if not cls.__module__ == "matplotlib.patches":
+            transmute = cbook._deprecate_method_override(
+                __class__.transmute, cls, since="3.4")
+            if transmute:
+                cls.__call__ = transmute
                 return
 
             __call__ = cls.__call__
