Summary

Add a common mixin class for handling invalidation.

Review Request #15170 — Created July 15, 2026 and submitted July 29, 2026, 7:48 p.m.

Information

Owner

chipx86

Repository

cryptozoology

Branch

master

Bugs

Depends On

Blocks

15168, 15172

Reviewers

Groups

beanbag-misc

People

Description

Sensitive data (keys, secrets) are intended to be invalidated early,

keeping the data safe and out of memory as best as possible.
This class implements this as a mixin class. It handles invalidation

when the instance falls out of scope, and allows the object to be used

as a context manager, invalidating on exit.

Testing Done

Unit tests pass.

Commits

Summary	ID
Add a common mixin class for handling invalidation. Sensitive data (keys, secrets) are intended to be invalidated early, keeping the data safe and out of memory as best as possible. This class implements this as a mixin class. It handles invalidation when the instance falls out of scope, and allows the object to be used as a context manager, invalidating on exit.	e8a39a80860703921eb6272749efef0bdf94ff88

Issues

Description	From	Last Updated
Instead of methods that raise NotImplementedError, how about subclassing abc.ABC and marking those with @abstractmethod?	david	July 22, 2026, 10:06 a.m.
Should probably change this to say self?	david	July 22, 2026, 10:06 a.m.
__exit__ never gets called with kwargs. Can we use the standard signature? def __exit( self, exc_type: type[BaseException] \| None, exc_value: …	david	July 21, 2026, 10:25 p.m.
If a subclass raises an exception from __init__, __del__ could get called on a partially-constructed instance. If the implementation of …	david	July 21, 2026, 10:27 p.m.
It's harmless here, but just to model goot behavior, can we call super().__init__()?	david	July 22, 2026, 10:06 a.m.
Since this is greenfield, can we use pytest test cases and real docstrings instead of a UnitTest subclass?	david	July 21, 2026, 10:29 p.m.
typo: exceptio -> exception	david	July 21, 2026, 10:29 p.m.
This was copy/pasted without updating to match the test.	david	July 21, 2026, 10:29 p.m.

flake8 passed.

JSHint passed.

Change Summary:

Removed the changes to BaseKey. Changing the order of commits.

Commits:

	Summary	ID
	Add a common mixin class for handling invalidation. Sensitive data (keys, secrets) are intended to be invalidated early, keeping the data safe and out of memory as best as possible. This class implements this as a mixin class. It handles invalidation when the instance falls out of scope, and allows the object to be used as a context manager, invalidating on exit.	e713456079169d085dbd89d8a9e54ae804b475cf
	Add a common mixin class for handling invalidation. Sensitive data (keys, secrets) are intended to be invalidated early, keeping the data safe and out of memory as best as possible. This class implements this as a mixin class. It handles invalidation when the instance falls out of scope, and allows the object to be used as a context manager, invalidating on exit.	7545462ea83693d7a39ab6c19687196949dfcf3d

Diff:

Revision 2 (+294)

Show changes

	cryptozoology/utils/invalidation.py
	cryptozoology/utils/tests/test_invalidatable_mixin.py

Checks run (2 succeeded)

flake8 passed.

JSHint passed.

cryptozoology/utils/invalidation.py (Diff revision 2)

The issue has been dropped. Show all issues

Instead of methods that raise NotImplementedError, how about subclassing abc.ABC and marking those with @abstractmethod?

chipx86

July 21, 2026, 10:33 p.m.

abc.ABC provides a hard-interface that makes it difficult to maintain forward-compatibility. If you use it in 1.0 and you add a new method using it in 1.1, you break interface compatibility because any subclass not implementing that method will break. It's great within an isolated codebase but bad for an extensible library.

cryptozoology/utils/invalidation.py (Diff revision 2)
The issue has been dropped. Show all issues
```
Should probably change this to say self?
```
1. chipx86
  
  July 21, 2026, 10:33 p.m.
  We don't do that anywhere else in our Python code.

cryptozoology/utils/invalidation.py (Diff revision 2)

The issue has been resolved. Show all issues

__exit__ never gets called with kwargs. Can we use the standard signature?

def __exit(
    self,
    exc_type: type[BaseException] | None,
    exc_value: BaseException | None,
    traceback: TracebackType | None,
) -> None:

cryptozoology/utils/invalidation.py (Diff revision 2)

The issue has been resolved. Show all issues

If a subclass raises an exception from __init__, __del__ could get called on a partially-constructed instance. If the implementation of invalidate() then assumes an attribute it set, it will AttributeError, and python will silently swallow it (I think it prints to stderr, but that's not the best for a library). This could leave the object not fully invalidated.

Can we document in here that the implementation must be able to handle partially-constructed instances, and cannot assume that all attributes have been set?

We also should document that this method needs to be idempotent, since it can get called first from __exit__ and then again from __del__

cryptozoology/utils/tests/test_invalidatable_mixin.py (Diff revision 2)

The issue has been resolved. Show all issues

It's harmless here, but just to model goot behavior, can we call super().__init__()?

chipx86

July 21, 2026, 10:33 p.m.

Sure. The mixin doesn't define __init__ and likely won't.

cryptozoology/utils/tests/test_invalidatable_mixin.py (Diff revision 2)

The issue has been dropped. Show all issues

Since this is greenfield, can we use pytest test cases and real docstrings instead of a UnitTest subclass?

chipx86

July 21, 2026, 10:33 p.m.

I don't want to use pytest alone for this package. I have a reply in another review somewhere, but there's benefits to unittest.TestCase that I'm employing, and I want consistency across test. I'd really like consistency across packages so we're not using different approaches everywhere. TestCase offers far better test organization and a lot of benefits around state management.

cryptozoology/utils/tests/test_invalidatable_mixin.py (Diff revision 2)
The issue has been resolved. Show all issues
```
typo: exceptio -> exception
```
cryptozoology/utils/tests/test_invalidatable_mixin.py (Diff revision 2)
The issue has been resolved. Show all issues
```
This was copy/pasted without updating to match the test.
```

Change Summary:


Updated __exit__ with explicit arguments.
Updated the docs for invalidate() to detail the expectations and requirements for subclasses.
Fixed a unit test name and docstring.

Commits:

	Summary	ID
	Add a common mixin class for handling invalidation. Sensitive data (keys, secrets) are intended to be invalidated early, keeping the data safe and out of memory as best as possible. This class implements this as a mixin class. It handles invalidation when the instance falls out of scope, and allows the object to be used as a context manager, invalidating on exit.	7545462ea83693d7a39ab6c19687196949dfcf3d
	Add a common mixin class for handling invalidation. Sensitive data (keys, secrets) are intended to be invalidated early, keeping the data safe and out of memory as best as possible. This class implements this as a mixin class. It handles invalidation when the instance falls out of scope, and allows the object to be used as a context manager, invalidating on exit.	e8a39a80860703921eb6272749efef0bdf94ff88

Diff:

Revision 3 (+330)

Show changes

	cryptozoology/utils/invalidation.py
	cryptozoology/utils/tests/test_invalidatable_mixin.py

Checks run (2 succeeded)

flake8 passed.

JSHint passed.

Ship it!

```
Ship It!
```

Status:: Completed
Change Summary:: Pushed to master (282d3e7)