Optimize setting units to None when they're already None.

anntzer · anntzer · commit 2990fd3d9b9b · 2019-12-12T23:53:27.000+01:00
Previously, we skipped the axis update when replacing a non-None unit by
the same unit, but (needlessly) not when replacing None by itself.

Also the newer implementation is simpler.
diff --git a/lib/matplotlib/axis.py b/lib/matplotlib/axis.py
@@ -1508,18 +1508,12 @@ def set_units(self, u):
         ----------
         u : units tag
         """
-        pchanged = False
-        if u is None:
-            self.units = None
-            pchanged = True
-        else:
-            if u != self.units:
-                self.units = u
-                pchanged = True
-        if pchanged:
-            self._update_axisinfo()
-            self.callbacks.process('units')
-            self.callbacks.process('units finalize')
+        if u == self.units:
+            return
+        self.units = u
+        self._update_axisinfo()
+        self.callbacks.process('units')
+        self.callbacks.process('units finalize')
         self.stale = True
 
     def get_units(self):
