Merge pull request matplotlib#20160 from meeseeksmachine/auto-backport-of-pr-20148-on-v3.4.x

Backport PR matplotlib#20148 on branch v3.4.x (FIX: MouseButton representation in boilerplate generated signatures)

Author: timhoffm

tools/boilerplate.py

@@ -24,9 +24,31 @@
 import numpy as np
 from matplotlib import _api, mlab
 from matplotlib.axes import Axes
+from matplotlib.backend_bases import MouseButton
 from matplotlib.figure import Figure
 
 
+# we need to define a custom str because py310 change
+# In Python 3.10 the repr and str representation of Enums changed from
+#
+#  str: 'ClassName.NAME' -> 'NAME'
+#  repr: '<ClassName.NAME: value>' -> 'ClassName.NAME'
+#
+# which is more consistent with what str/repr should do, however this breaks
+# boilerplate which needs to get the ClassName.NAME version in all versions of
+# Python. Thus, we locally monkey patch our preferred str representation in
+# here.
+#
+# bpo-40066
+# https://github.com/python/cpython/pull/22392/
+def enum_str_back_compat_patch(self):
+    return f'{type(self).__name__}.{self.name}'
+
+# only monkey patch if we have to.
+if str(MouseButton.LEFT) != 'MouseButton.Left':
+    MouseButton.__str__ = enum_str_back_compat_patch
+
+
 # This is the magic line that must exist in pyplot, after which the boilerplate
 # content will be appended.
 PYPLOT_MAGIC_HEADER = (