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FIX: Handle AxesWidget cleanup after failed init #30935

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Merged
timhoffm merged 5 commits into from
Jan 24, 2026
Merged

FIX: Handle AxesWidget cleanup after failed init #30935

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5bc69c9
FIX: Handle AxesWidget cleanup after failed init
larrybradley Jan 5, 2026
4963e01
Apply code review suggestions
larrybradley Jan 8, 2026
adfd6bb
Update lib/matplotlib/tests/test_widgets.py
larrybradley Jan 8, 2026
b60db73
Remove __del__ method
larrybradley Jan 23, 2026
d725b13
Remove AxesWidget.__del__ from widgets.pyi
larrybradley Jan 23, 2026
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Remove __del__ method
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@larrybradley
larrybradley committed Jan 23, 2026
commit b60db73f4de57246e855fb7f676217be4109f084
7 changes: 4 additions & 3 deletions lib/matplotlib/tests/test_widgets.py
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Original file line number Diff line number Diff line change
Expand Up @@ -518,9 +518,10 @@ def test_rectangle_resize_square_center_aspect(ax, use_data_coordinates):


def test_axeswidget_del_on_failed_init():
"""Test that __del__ works correctly when __init__ fails."""
# __del__ is called implicitly as part of a failed initialization
# here, which could create an unraisable exception in __del__.
"""
Test that an unraisable exception is not created when initialization
fails.
"""
# Pytest would fail the test if such an exception occurred.
fig, ax = plt.subplots()
with pytest.raises(TypeError, match="unexpected keyword argument 'undefined'"):
Expand Down
15 changes: 4 additions & 11 deletions lib/matplotlib/widgets.py
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Original file line number Diff line number Diff line change
@@ -1,3 +1,3 @@
"""
GUI neutral widgets
===================
Expand All @@ -14,6 +14,7 @@
import enum
import functools
import itertools
import weakref
from numbers import Integral, Number

from cycler import cycler
Expand Down Expand Up @@ -120,16 +121,6 @@
self._cids = []
self._blit_background_id = None

def __del__(self):
blit_background_id = getattr(self, '_blit_background_id', None)
# __del__ may be called on a partially initialized object, e.g.,
# when __init__ raises. Therefore, we handle missing attributes
# gracefully.
if blit_background_id is not None:
canvas = getattr(self, 'canvas', None)
if canvas is not None:
canvas._release_blit_background_id(blit_background_id)

canvas = property(
lambda self: getattr(self.ax.get_figure(root=True), 'canvas', None)
)
Expand Down Expand Up @@ -170,7 +161,9 @@
good enough for all existing widgets.
"""
if self._blit_background_id is None:
self._blit_background_id = self.canvas._get_blit_background_id()
bbid = self.canvas._get_blit_background_id()
weakref.finalize(self, self.canvas._release_blit_background_id, bbid)
self._blit_background_id = bbid
self.canvas._blit_backgrounds[self._blit_background_id] = background

def _load_blit_background(self):
Expand Down
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