MNT: Fix double evaluation of _LazyTickList

Closes matplotlib#28908. The final instance.majorTicks list must be assigned after running `_get_tick()` because that may call `reset_ticks()`, which invalidates a previous set list. We still temporarily assign an empty tick list to instance.majorTicks, because `_get_tick()` may rely on that attibute to exist.
timhoffm · Sep 30, 2024 · 017118e · 017118e
1 parent 6404c95
commit 017118e
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diff --git a/doc/users/next_whats_new/axes_creation_speedup.rst b/doc/users/next_whats_new/axes_creation_speedup.rst
diff --git a/lib/matplotlib/axis.py b/lib/matplotlib/axis.py
@@ -538,17 +538,19 @@ def __get__(self, instance, owner):
             # instance._get_tick() can itself try to access the majorTicks
             # attribute (e.g. in certain projection classes which override
             # e.g. get_xaxis_text1_transform).  In order to avoid infinite
-            # recursion, first set the majorTicks on the instance to an empty
-            # list, then create the tick and append it.
+            # recursion, first set the majorTicks on the instance temporarily
+            # to an empty lis. Then create the tick; note that _get_tick()
+            # may call reset_ticks(). Therefore, the final tick list is
+            # created and assigned afterwards.
             if self._major:
                 instance.majorTicks = []
                 tick = instance._get_tick(major=True)
-                instance.majorTicks.append(tick)
+                instance.majorTicks = [tick]
                 return instance.majorTicks
             else:
                 instance.minorTicks = []
                 tick = instance._get_tick(major=False)
-                instance.minorTicks.append(tick)
+                instance.minorTicks = [tick]
                 return instance.minorTicks