WIP: Custom frozen dataclasses

[tony]

Resolves #588

Summary by Sourcery

Tests:

• Adds comprehensive tests for the frozen_dataclass decorator, covering initialization, immutability, inheritance, edge cases, nested mutability, bidirectional references, and mutation methods.

[sourcery-ai]

Reviewer's Guide by Sourcery

This pull request introduces a frozen_dataclass decorator that allows creating immutable dataclasses that inherit from mutable ones. It includes comprehensive tests and configurations for mypy and ruff.

Class diagram for frozen_dataclass decorator

classDiagram
    class frozen_dataclass {
        +__init__(cls: type[_T]) type[_T]
    }
    class dataclasses.dataclass {
        +__init__(frozen: bool)
    }
    class cls {
        +__setattr__(name: str, value: t.Any) None
        +__delattr__(name: str) None
        -_frozen: bool
    }
    frozen_dataclass --|> dataclasses.dataclass: Uses
    frozen_dataclass --|> cls: Decorates

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File-Level Changes

Change	Details	Files
Introduces a frozen_dataclass decorator to create immutable dataclasses inheriting from mutable ones.	Adds a frozen_dataclass decorator. Applies @dataclasses.dataclass(frozen=False) to preserve dataclass generation. Overrides __setattr__ and __delattr__ to prevent changes after initialization. Adds a _frozen attribute to control immutability. Includes documentation and examples for the decorator.	src/libtmux/_internal/frozen_dataclass.py
Adds tests for the frozen_dataclass decorator, covering initialization, immutability, inheritance, and edge cases.	Creates base and snapshot dataclasses for testing. Tests immutability by attempting to modify fields and verifying AttributeError exceptions. Tests inheritance from mutable base classes. Tests internal attribute modification. Tests nested mutability. Tests bidirectional references. Adds parametrized tests for dimensions and frozen flag behavior. Adds tests for mutation methods and inheritance behavior.	tests/_internal/test_frozen_dataclass.py
Configures mypy to ignore method-assign errors for the frozen_dataclass module.	Adds a mypy override to disable method-assign errors for the libtmux._internal.frozen_dataclass module.	pyproject.toml
Configures ruff to ignore B010 (set-attr-with-constant) errors for the frozen_dataclass module.	Adds a ruff ignore rule to disable B010 errors for the src/libtmux/_internal/frozen_dataclass.py module.	pyproject.toml

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[codecov]

Codecov Report

Attention: Patch coverage is 84.23645% with 32 lines in your changes missing coverage. Please review.

Project coverage is 80.25%. Comparing base (5803841) to head (0975cfd).

Files with missing lines	Patch %	Lines
src/libtmux/_internal/frozen_dataclass_sealable.py	79.25%	20 Missing and 8 partials ⚠️
src/libtmux/_internal/frozen_dataclass.py	92.85%	1 Missing and 1 partial ⚠️
.../_internal/frozen_dataclass_sealable/test_basic.py	95.00%	1 Missing and 1 partial ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master     #586      +/-   ##
==========================================
+ Coverage   79.83%   80.25%   +0.42%     
==========================================
  Files          22       25       +3     
  Lines        1914     2117     +203     
  Branches      294      338      +44     
==========================================
+ Hits         1528     1699     +171     
- Misses        266      288      +22     
- Partials      120      130      +10     

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[tony]

@sourcery-ai review

[sourcery-ai]

Hey @tony - I've reviewed your changes - here's some feedback:

Overall Comments:

• Consider adding a note about the performance implications of using __setattr__ and __delattr__.
• It would be helpful to include a warning in the documentation about the potential for users to bypass the immutability by modifying the _frozen attribute.

Here's what I looked at during the review

• 🟢 General issues: all looks good
• 🟢 Security: all looks good
• 🟡 Testing: 1 issue found
• 🟢 Complexity: all looks good
• 🟢 Documentation: all looks good

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[sourcery-ai]

issue (testing): Edge case: Unfreezing via _frozen attribute

Although tested, the ability to unfreeze by modifying _frozen is a security risk. Consider making _frozen a property with a private setter to prevent this or document this behavior clearly as a known limitation.