fix: handle tuple dtype in DataType repr and error message

[CedricConday]

Summary

Fixes #989.

DataType documents and supports dtype as a type or a tuple[type] — check() already uses isinstance(data, self.dtype), which is tuple-aware. But __repr__ and the type-mismatch error in check() formatted the dtype via self.dtype.__name__, which raises AttributeError: 'tuple' object has no attribute '__name__' whenever dtype is a tuple. So repr(DataType("x", (list, tuple))) crashes instead of returning a string.

Changes

• Added a small _dtype_name() helper that renders either a single type or a tuple of types.
• Used it in __repr__ and in the check() error message.

Testing

• Added regression tests: repr of a tuple-dtype DataType no longer raises and lists both type names; a type mismatch against a tuple dtype raises a readable DataError (not AttributeError). Both fail on master and pass with this change.
• ruff check clean; existing TestDataType tests pass.

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Disclosure: authored with AI assistance (Claude Code); reviewed by me and I'll shepherd it through review.

Summary by CodeRabbit

• Bug Fixes
  • Improved how data type information is shown in object summaries and error messages, including support for multiple allowed data types.
  • Fixed validation so mismatched data types now produce a clear, consistent error instead of an unexpected failure.
• Tests
  • Added regression coverage for tuple-based data type formatting and validation.

[coderabbitai]

No actionable comments were generated in the recent review. 🎉

ℹ️ Recent review info

⚙️ Run configuration

Configuration used: Organization UI

Review profile: CHILL

Plan: Pro

Run ID: 72da9943-c4a2-4c22-a75b-5bb4a8dd66eb

📥 Commits

Reviewing files that changed from the base of the PR and between a7a50bf and 45338d8.

📒 Files selected for processing (2)

• dpdata/data_type.py
• tests/test_custom_data_type.py

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📝 Walkthrough

Walkthrough

Adds a _dtype_name() helper in dpdata/data_type.py that produces a readable string for both single types and tuples of types. DataType.__repr__ and DataType.check() are updated to use this helper, fixing AttributeError when dtype is a tuple. Two regression tests are added.

Tuple dtype fix

Layer / File(s)	Summary
_dtype_name helper and DataType formatting fixes dpdata/data_type.py	Adds _dtype_name(dtype) that joins type names for tuples; __repr__ and check() dtype-mismatch error message both switch from self.dtype.__name__ to _dtype_name(self.dtype).
Regression tests for tuple dtype tests/test_custom_data_type.py	Imports DataError and adds test_repr_tuple_dtype and test_check_tuple_dtype_error_message to verify correct repr output and proper DataError raising for tuple dtypes.

Estimated code review effort

🎯 1 (Trivial) | ⏱️ ~4 minutes

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title clearly summarizes the main fix: handling tuple dtypes in DataType formatting and error messages.
Linked Issues check	✅ Passed	The code and tests address issue #989 by preventing tuple dtypes from crashing repr() and mismatch errors.
Out of Scope Changes check	✅ Passed	The changes stay focused on tuple dtype formatting and regression tests, with no unrelated additions.
Docstring Coverage	✅ Passed	Docstring coverage is 100.00% which is sufficient. The required threshold is 80.00%.

✨ Finishing Touches

🧪 Generate unit tests (beta)

• Create PR with unit tests

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[codspeed-hq]

Merging this PR will degrade performance by 10.13%

⚠️ Unknown Walltime execution environment detected

Using the Walltime instrument on standard Hosted Runners will lead to inconsistent data.

For the most accurate results, we recommend using CodSpeed Macro Runners: bare-metal machines fine-tuned for performance measurement consistency.

⚠️ Different runtime environments detected

Some benchmarks with significant performance changes were compared across different runtime environments,
which may affect the accuracy of the results.

Open the report in CodSpeed to investigate

❌ 1 regressed benchmark
✅ 1 untouched benchmark

Warning

Please fix the performance issues or acknowledge them on CodSpeed.

Performance Changes

	Mode	Benchmark	BASE	HEAD	Efficiency
❌	WallTime	test_import	10.1 ms	11.2 ms	-10.13%

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 CedricConday:fix/datatype-tuple-dtype-repr-989 (45338d8) with master (a7a50bf)}

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 86.70%. Comparing base (a7a50bf) to head (45338d8).

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #1005      +/-   ##
==========================================
+ Coverage   86.68%   86.70%   +0.01%     
==========================================
  Files          89       89              
  Lines        8120     8124       +4     
==========================================
+ Hits         7039     7044       +5     
+ Misses       1081     1080       -1     

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