Merge pull request matplotlib#13602 from anntzer/unhashable

Deprecate cbook.is_hashable.

Author: jklymak

doc/api/next_api_changes/2019-03-06-AL.rst

@@ -0,0 +1,5 @@
+Deprecations
+````````````
+
+``cbook.is_hashable`` is deprecated (use
+``isinstance(..., collections.abc.Hashable)`` instead).

lib/matplotlib/cbook/__init__.py

@@ -350,6 +350,7 @@ def iterable(obj):
     return True
 
 
+@deprecated("3.1", alternative="isinstance(..., collections.abc.Hashable)")
 def is_hashable(obj):
     """Returns true if *obj* can be hashed"""
     try:

lib/matplotlib/legend.py

@@ -754,18 +754,15 @@ def get_legend_handler(legend_handler_map, orig_handle):
         method-resolution-order. If no matching key is found, it
         returns ``None``.
         """
-        if is_hashable(orig_handle):
-            try:
-                return legend_handler_map[orig_handle]
-            except KeyError:
-                pass
-
+        try:
+            return legend_handler_map[orig_handle]
+        except (TypeError, KeyError):  # TypeError if unhashable.
+            pass
         for handle_type in type(orig_handle).mro():
             try:
                 return legend_handler_map[handle_type]
             except KeyError:
                 pass
-
         return None
 
     def _init_legend_box(self, handles, labels, markerfirst=True):