Catch exceptions that occur in callbacks. #7197
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Uncaught exceptions are fatal to PyQt5 so we catch anything that occurs
in a callback of the canvas class.
e.g.
```
from matplotlib import pyplot as plt
plt.gca().figure.canvas.mpl_connect(
"axes_enter_event", lambda event: 1 / 0)
plt.show()
```
used to crash matplotlib upon entering the axes.
| @@ -542,6 +542,21 @@ def process(self, s, *args, **kwargs): | |||
| except ReferenceError: | |||
| self._remove_proxy(proxy) | |||
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| def safe_process(self, s, on_error, *args, **kwargs): | |||
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Is there any changes you will be calling with an on_error different from traceback.print_exc?
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Yes, close_event completely silences out specific exception types.
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We vendored and modified the callback registry at my day-job (https://github.com/NSLS-II/bluesky/blob/master/bluesky/utils.py#L159) to add a stateful flag to the control if callbacks are allowed to raise or not. I think that is a better option here as it would require less change to the code base, provides a way to go back to the previous behavior, and does not leave an 'orphaned' method on the callback registry. |
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The problem of the flag you propose is that exceptions are completely swallowed. An alternative would be to replace the flag by a callback stored as an attribute... say Side note for @tacaswell: for your own implementation, given that it is Py3 only you could probably use |
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@anntzer I agree, that is a better idea than a flag. |
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👍 to the idea of using a callable attribute |
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The problem is that we need a half-decent method for locally patching this attribute when needed. However, the only place where this needs to happen is in (the earlier version wrapped |
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The |
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Closing in favor of #9063 |
Uncaught exceptions are fatal to PyQt5 so we catch anything that occurs
in a callback of the canvas class.
e.g.
used to crash matplotlib upon entering the axes.
More general than #7052.