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[Bug]: Bad type hint in _AxesBase.twinx() #28624
Description
Bug summary
Incorrect type annotation for _AxesBase.twinx() (should be Self, not _AxesBase).
Code for reproduction
import matplotlib.pyplot as plt
import numpy as np
# First create some toy data:
x = np.linspace(0, 2 * np.pi, 400)
y = np.sin(x**2)
z = np.cos(x**2)
# Create four polar Axes and access them through the returned array
fig, axsA = plt.subplots()
axsA.plot(x, y)
axsB = axsA.twinx()
axsB.plot(x, z) # <-- Cannot access attribute "plot" for class "_AxesBase"Actual outcome
axsB is of type _AxesBase
Expected outcome
The type of axsB should be the same as the type of axsA.
Matplotlib Version
3.9.1
Activity
randolf-scholz commentedon Jul 29, 2024
Potentially fixing this requires adding
typing_extensionsas a dependency, sincetyping.Selfis not available in 3.10.Otherwise, users might not have it in their virtual environment when installing
matplotlib, leaving the stubs broken.randolf-scholz commentedon Jul 29, 2024
I made a provisional PR #28625, maintainers likely want to discuss first whether to add the extra dependency. Although imo
typing_extensionsis kind of must-have if you want to type the library as it is the official place for backporting new typing features.