Use itertools.count for renderer unique ID.

QuLogic · QuLogic · commit 2005738a8dca · 2017-06-03T20:28:42.000-04:00
As suggested by @anntzer.
diff --git a/lib/matplotlib/backend_bases.py b/lib/matplotlib/backend_bases.py
@@ -41,6 +41,7 @@
 from contextlib import contextmanager
 import importlib
 import io
+import itertools
 import os
 import sys
 import time
@@ -101,8 +102,9 @@
 
 
 # Used to ensure that caching based on renderer id() is unique without being as
-# expensive as a real UUID.
-_unique_renderer_id = 0
+# expensive as a real UUID. 0 is used for renderers that don't derive from
+# here, so start at 1.
+_unique_renderer_id = itertools.count(1)
 
 
 def register_backend(format, backend, description=None):
@@ -217,25 +219,14 @@ class RendererBase(object):
 
     """
     def __init__(self):
-        self._id = None
+        # A lightweight id for unique-ification purposes. Along with id(self),
+        # the combination should be unique enough to use as part of a cache key.
+        self._uid = next(_unique_renderer_id)
+
         self._texmanager = None
 
         self._text2path = textpath.TextToPath()
 
-    @property
-    def _uid(self):
-        """
-        A lightweight id for unique-ification purposes.
-
-        Along with id(self), this combination should be unique enough to use as
-        part of a caching key.
-        """
-        if self._id is None:
-            global _unique_renderer_id
-            _unique_renderer_id += 1
-            self._id = _unique_renderer_id
-        return self._id
-
     def open_group(self, s, gid=None):
         """
         Open a grouping element with label *s*. If *gid* is given, use
diff --git a/lib/matplotlib/backends/backend_mixed.py b/lib/matplotlib/backends/backend_mixed.py
@@ -5,6 +5,7 @@
 
 import six
 
+import matplotlib.backend_bases
 from matplotlib.backends.backend_agg import RendererAgg
 from matplotlib.tight_bbox import process_figure_for_rasterizing
 
@@ -49,7 +50,9 @@ def __init__(self, figure, width, height, dpi, vector_renderer,
         if raster_renderer_class is None:
             raster_renderer_class = RendererAgg
 
-        self._id = None
+        # See matplotlib.backend_bases.RendererBase._uid.
+        self._uid = next(matplotlib.backend_bases._unique_renderer_id)
+
         self._raster_renderer_class = raster_renderer_class
         self._width = width
         self._height = height
@@ -81,18 +84,6 @@ def __init__(self, figure, width, height, dpi, vector_renderer,
         _text2path _get_text_path_transform height width
         """.split()
 
-    @property
-    def _uid(self):
-        """
-        See matplotlib.backend_bases.RendererBase._uid.
-        """
-        if self._id is None:
-            from matplotlib import backend_bases
-            backend_bases._unique_renderer_id
-            backend_bases._unique_renderer_id += 1
-            self._id = backend_bases._unique_renderer_id
-        return self._id
-
     def _set_current_renderer(self, renderer):
         self._renderer = renderer
 
