gh-144191: Dataclasses single field ordering

[whyvineet]

Simplify single-field dataclass ordering comparisons
#144191

• Issue: Can dataclass ordering avoid tuple wrappers for single field comparisons? #144191

[bedevere-app]

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[johnslavik]

Thanks! You can wait for the green light from Eric before going forward or add tests for this even now. I'd probably change test_1_field_compare. And of course a news entry, too.

[johnslavik]

This is how I'd approach it:

Suggested change

	if len(flds) == 1:
	self_expr = f"self.{flds[0].name}"
	other_expr = f"other.{flds[0].name}"
	else:
	self_expr = _tuple_str('self', flds)
	other_expr = _tuple_str('other', flds)
	match flds:
	# Special-case single field comparisons. See GH-144191.
	case [single_fld]:
	self_expr = f'self.{single_fld.name}'
	other_expr = f'other.{single_fld.name}'
	case _:
	self_expr = _tuple_str('self', flds)
	other_expr = _tuple_str('other', flds)

[whyvineet]

Thanks! I’ve updated the logic using match/case. It’s more readable and makes the intent clearer.

[bedevere-app]

Most changes to Python require a NEWS entry. Add one using the blurb_it web app or the blurb command-line tool.

If this change has little impact on Python users, wait for a maintainer to apply the skip news label instead.