Made set_and_wait_for_other_value still still raise a TimeoutError if there is no __name__ on the matcher

[DominicOram]

Fixes #1122

To test:

• Confirm new test fails on main but passes here

[vredchenko]

This was auto-generated by Claude Code:

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PR Review

Thank you for fixing this issue! The PR successfully addresses the bug where matchers without __name__ attributes would cause an AttributeError instead of a proper TimeoutError.

Issues Found

🔴 Critical: Mutating the matcher object

The current approach mutates the matcher object by setting matcher.__name__:

except TimeoutError as exc:
    if not hasattr(matcher, "__name__"):
        matcher.__name__ = "supplied_function"  # ⚠️ Mutates the object
    raise TimeoutError(...)

Problems:

• Creates unexpected side effects on the matcher object
• Could affect code that reuses the same matcher instance
• Potential race conditions with concurrent calls using the same matcher

Recommended fix: Use getattr() to avoid mutation:

except TimeoutError as exc:
    matcher_name = getattr(matcher, "__name__", "<callable>")
    raise TimeoutError(
        f"{match_signal.name} value didn't match value from"
        f" {matcher_name}() in {timeout}s"
    ) from exc

This is:

• ✅ Safer (no side effects)
• ✅ Cleaner (more Pythonic)
• ✅ Simpler (fewer lines)
• ✅ Functionally equivalent

🟡 Medium: Consider using type information

The fallback name "supplied_function" is generic. Consider using type(matcher).__name__ for more context:

matcher_name = getattr(matcher, "__name__", f"<{type(matcher).__name__}>")

This would produce error messages like:

• "match_signal value didn't match value from <NoNameCallable>() in 0.01s"
• "match_signal value didn't match value from <partial>() in 0.01s"

Which provides more debugging information.

Test Suggestions

Add test for functools.partial

Since issue #1122 specifically mentioned functools.partial as the trigger, consider adding an explicit test:

from functools import partial
 
async def test_partial_matcher_timeout_error():
    """Test that functools.partial matcher properly raises TimeoutError"""
    set_signal = epics_signal_rw(int, "pva://signal")
    match_signal = epics_signal_rw(int, "pva://match_signal")
 
    await set_signal.connect(mock=True)
    await match_signal.connect(mock=True)
 
    with pytest.raises(asyncio.TimeoutError):
        await set_and_wait_for_other_value(
            set_signal, 20, match_signal, partial(lambda x, y: x == y, 20), timeout=0.01
        )

Optional: Assert error message format

with pytest.raises(asyncio.TimeoutError, match=r"match_signal value didn't match"):
    await set_and_wait_for_other_value(...)

Positive Aspects

✅ Correctly identifies and fixes the core issue
✅ Good test coverage with realistic scenario
✅ Minimal, focused change
✅ Preserves exception chain with from exc

Recommendation

Approve with changes - The fix works, but please replace the mutation approach with getattr() for safety and cleanliness. The current implementation could cause unexpected side effects.