Add auto-disconnecting mixin for QObject #5951
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drew2a
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Jan 25, 2021
| logger = logging.getLogger('QAutoDisconnectingMixin') | ||
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| class QAutoDisconnectingMixin: |
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This is the main improvement for the PR.
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Indeed, connecting/disconnecting signals is a fragile topic in PyQT. I'm afraid it can bring more trouble because of potential interference with different QT version on different platforms, etc. I would prefer adding a separate warning ("caveat") chapter to our developer's guidelines instead. And of course, point out the PR reviewers to pay special attention to signals. |
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This PR adds a Mixin that can disconnect QR signals automatically.
Based on the discussoin #5949 and regarding @ichorid experience, it is necessary to manually disconnect a QT signal. This should help for avoiding memory leaks like #5934
The current version of the Mixin is working with no errors (at least for me).
The pitfalls
During developing this Mixin I saw a lot of "strange" bugs when python crashed with the following error: "Process finished with exit code 139 (interrupted by signal 11: SIGSEGV)".
They occurred, for example, when trying to log some of the signals:
And when trying to use (some) of the signals as a key in a dictionary:
Another case. Some signals lead to a python crash if you try to disconnect all callbacks at once:
Therefore:
id(signal)is using for logging and as a key for a dictionaryConclusion
The Mixing is working for me with no errors, but I consider the QT disconnect mechanism is fragile.
Unfortunately, I see more risks for merging this PR rather than benefits.
What do you think about that?