[hamid-digitalmarketer]

Summary

Fixes #1920

Problem

Python 3.13 introduced copy.replace(obj, **changes) which relies on the __replace__() protocol method. Currently, BaseContainer does not define __replace__, preventing users from using copy.replace on containers like Result, Maybe, IO, etc.

Solution

• Implemented __replace__(self: _ContainerType, **changes: Any) -> _ContainerType on BaseContainer in returns/primitives/container.py:
  • Accepts inner_value (the constructor parameter name) or _inner_value (the slot attribute name) and constructs a new instance of the same type.
  • Raises a descriptive TypeError if unexpected keyword arguments are provided or if both inner_value and _inner_value are specified.
  • Calling without arguments returns an equal copy (self.__class__(self._inner_value)).
• Implemented specialized __replace__ on _Nothing in returns/maybe.py:
  • Returns self when inner_value is None.
  • Raises a TypeError if a non-None value is supplied to preserve the empty state semantics.

Tests Added

Added tests/test_primitives/test_container/test_base_container/test_replace.py:

• Property-based testing with Hypothesis verifying replacement with integers and text.
• Parametrized tests across concrete container types (Success, Failure, Some, IO, Nothing).
• Error-handling assertions for unexpected keyword arguments and ambiguous parameter values.
• Standard library copy.replace integration test (conditionally executed on Python 3.13+).

Verification

• Tested with pytest --no-cov tests/test_primitives/test_container/test_base_container/test_replace.py:

  10 passed, 1 skipped in 0.82s
  

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[codspeed]

Merging this PR will degrade performance by 10.59%

1 warning, 1 note

⚠️ Base and head ran on different runner types

Some benchmarks with significant performance changes were compared across different runner types, so the changes might not come from the code. Run base and head on the same runner type, or use CodSpeed Macro Runners for more stable results.

Learn more about Macro Runners

Open the report in CodSpeed to investigate

ℹ️ 2 benchmarks have no flamegraph

The flamegraph wasn't generated: the symbols of the profiling trace could not be resolved, because no information about the language frames was collected.

See affected benchmarks

❌ 1 regressed benchmark
✅ 21 untouched benchmarks

Warning

Please fix the performance issues or acknowledge them on CodSpeed.

Performance Changes

	Mode	Benchmark	BASE	HEAD	Efficiency
❌	CPU Simulation	test_safe_decorator	67.8 µs	75.8 µs	-10.59%

Tip

Investigate this regression by commenting @codspeedbot fix this regression on this PR, or directly use the CodSpeed MCP with your agent.

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_{Comparing hamid-digitalmarketer:feat/issue-1920-copy-replace-container (9664961) with master (ea76fb5)}