fix(python): user defined __jsii_proxy_class attributes are not preserved #4625
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mergify[bot] merged 2 commits intomainfrom Aug 29, 2024
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fix(python): user defined __jsii_proxy_class attributes are not preserved #4625mergify[bot] merged 2 commits intomainfrom
__jsii_proxy_class attributes are not preserved #4625mergify[bot] merged 2 commits intomainfrom
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mrgrain
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Aug 29, 2024
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Thank you for contributing! ❤️ I will now look into making sure the PR is up-to-date, then proceed to try and merge it! |
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Merging (with squash)... |
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Aug 30, 2024
…served (#4625) In #4611, we added the `_jsii_proxy_class__` attributes to the `@jsii.interface` implementations. This was required in order to comply with `typeguard` protocol checking. We didn't implement it correctly, accidentally overriding user defined proxy classes. ## Note I have been wrecking my brain trying to understand if this bug has any runtime implications, and I couldn't find any. #### How so? At runtime, from what I could gather, the `__jsii_proxy_class__` attribute is only used when we try to instantiate a subclass of an abstract class: https://github.com/aws/jsii/blob/dc77d6c7016bcb7531f6e374243410f969ea1fbf/packages/%40jsii/python-runtime/src/jsii/_reference_map.py#L65-L70 However, for abstract classes, we assign an explicit value to `__jsii_proxy_class__`: https://github.com/aws/jsii/blob/dc77d6c7016bcb7531f6e374243410f969ea1fbf/packages/jsii-pacmak/lib/targets/python.ts#L1496-L1501 Luckily, this happens **AFTER** the `@jsii.implements` decorator has finished, thus overriding the mistake in the decorator. Presumably, this would still be a problem for user defined abstract classes (since they don't have this assignment). However, reference resolving for user defined classes is done via native reference lookup: https://github.com/aws/jsii/blob/dc77d6c7016bcb7531f6e374243410f969ea1fbf/packages/%40jsii/python-runtime/src/jsii/_reference_map.py#L48-L54 This is also why I couldn't come up with a real life test case, and had to resort to an artificial one. --- By submitting this pull request, I confirm that my contribution is made under the terms of the [Apache 2.0 license]. [Apache 2.0 license]: https://www.apache.org/licenses/LICENSE-2.0
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In #4611, we added the
_jsii_proxy_class__attributes to the@jsii.interfaceimplementations. This was required in order to comply withtypeguardprotocol checking. We didn't implement it correctly, accidentally overriding user defined proxy classes.Note
I have been wrecking my brain trying to understand if this bug has any runtime implications, and I couldn't find any.
How so?
At runtime, from what I could gather, the
__jsii_proxy_class__attribute is only used when we try to instantiate a subclass of an abstract class:jsii/packages/@jsii/python-runtime/src/jsii/_reference_map.py
Lines 65 to 70 in dc77d6c
However, for abstract classes, we assign an explicit value to
__jsii_proxy_class__:jsii/packages/jsii-pacmak/lib/targets/python.ts
Lines 1496 to 1501 in dc77d6c
Luckily, this happens AFTER the
@jsii.implementsdecorator has finished, thus overriding the mistake in the decorator.Presumably, this would still be a problem for user defined abstract classes (since they don't have this assignment). However, reference resolving for user defined classes is done via native reference lookup:
jsii/packages/@jsii/python-runtime/src/jsii/_reference_map.py
Lines 48 to 54 in dc77d6c
This is also why I couldn't come up with a real life test case, and had to resort to an artificial one.
By submitting this pull request, I confirm that my contribution is made under the terms of the Apache 2.0 license.